Crowd Pleasing Breakfast Casserole for a Large Group Brunch

Name: Crowd Pleasing Breakfast Casserole for a Large Group Brunch
Prep time: 25 min
Cook time: 50 min
Total time: 9 h 15 min
Yield: 12 servings
Cuisine: American
Ingredients: 500 g lean turkey sausage (casings removed, crumbled); 2 medium sweet potatoes (peeled and cut into 1cm cubes, about 600g total); 1 tablespoon olive oil; 1 large red bell pepper (diced small); 1 medium yellow onion (diced small); 3 cloves garlic (minced); 100 g baby spinach (roughly chopped); 4 stalks spring onions (sliced, green and white parts separated); 8 large whole eggs; 6 large egg whites (from fresh eggs or carton); 180 ml unsweetened almond milk (or low fat dairy milk); 1 teaspoon smoked paprika; 0.5 teaspoon ground cumin; 0.5 teaspoon dried oregano; 0.75 teaspoon fine sea salt (divided); 0.5 teaspoon black pepper (divided); 100 g reduced fat sharp cheddar cheese (freshly grated, divided); 2 tablespoons fresh flat leaf parsley (chopped, to serve); 1 teaspoon olive oil spray or light olive oil (for greasing the baking dish)

High ProteinGluten-FreeMeal PrepNut-Free

Prep Time25 min

Cook Time50 min

Servings12

Calories278 kcal

Health Score7/10

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Crowd Pleasing Breakfast Casserole for a Large Group Brunch

When you are feeding a big table of hungry people on a weekend morning, the last thing you want is to be flipping individual omelettes or scrambling eggs in batches. This crowd pleasing breakfast casserole for a large group brunch solves all of that in one big, golden, bubbling dish. It serves 12 generously, it can be assembled the night before, and it delivers real nutritional value rather than just comfort. Think of it as the kind of breakfast that makes everyone go quiet for a moment when they take their first bite.

The base of this casserole is a combination of lean turkey sausage, sweet potato, and a full rainbow of vegetables including red bell pepper, baby spinach, and spring onions. Sweet potato takes the place of white bread or heavy cream, giving you natural fibre, complex carbohydrates, and a gentle sweetness that balances the savoury egg custard beautifully. The egg mixture uses a blend of whole eggs and egg whites, which keeps the protein content seriously high while reducing the overall fat compared to a traditional all-yolk version. A modest amount of reduced fat sharp cheddar melts into every layer, giving you that satisfying cheesy pull without overdoing the saturated fat.

Nutrition does not have to mean bland, and this casserole proves it. Fresh garlic, smoked paprika, ground cumin, and dried oregano build a warm, deeply savoury flavour profile that makes each square taste like something far more indulgent than it actually is. The turkey sausage brings its own seasoning, and when it is browned properly it adds those delicious caramelised bits throughout the dish. The sweet potato cubes roast slightly during the bake, becoming just tender enough to hold their shape while soaking up all that spiced egg mixture. Every single forkful has something going on, and that is exactly what keeps people coming back for seconds at a brunch table.

This recipe is a brilliant choice for holiday mornings, birthday brunches, meal prep for a busy week, or any occasion where you need something reliable that travels and reheats well. You can assemble the whole thing on Saturday evening, cover it tightly, and slide it into the refrigerator overnight. On Sunday morning, pull it out while the oven preheats, let it sit on the counter for about 15 minutes to take the chill off, then bake until puffed and golden. By the time your guests have poured their coffee and settled in, breakfast is ready. Clean up is minimal, everyone gets a proper meal, and you get to actually enjoy the morning rather than spending it at the stove.

Ingredients

Serves:12

500 g lean turkey sausage (casings removed, crumbled)
2 medium sweet potatoes (peeled and cut into 1cm cubes, about 600g total)
1 tablespoon olive oil
1 large red bell pepper (diced small)
1 medium yellow onion (diced small)
3 cloves garlic (minced)
100 g baby spinach (roughly chopped)
4 stalks spring onions (sliced, green and white parts separated)
8 large whole eggs
6 large egg whites (from fresh eggs or carton)
180 ml unsweetened almond milk (or low fat dairy milk)
1 teaspoon smoked paprika
0.5 teaspoon ground cumin
0.5 teaspoon dried oregano
0.8 teaspoon fine sea salt (divided)
0.5 teaspoon black pepper (divided)
100 g reduced fat sharp cheddar cheese (freshly grated, divided)
2 tablespoons fresh flat leaf parsley (chopped, to serve)
1 teaspoon olive oil spray or light olive oil (for greasing the baking dish)

Instructions

1
Preheat your oven to 200 degrees Celsius (180 fan, 400 Fahrenheit). Lightly grease a 9x13 inch baking dish with olive oil spray and set aside.
If you are making this ahead, have your baking dish ready so assembly is quick and straightforward.
2
Spread the cubed sweet potato onto a large rimmed baking tray and drizzle with the tablespoon of olive oil. Season with a pinch of salt and pepper, toss to coat, and roast for 20 minutes until just tender and lightly golden at the edges. Remove from the oven and set aside.
Do not crowd the sweet potato cubes on the tray or they will steam rather than roast. Use two trays if needed.
3
While the sweet potato roasts, heat a large non-stick frying pan over medium-high heat. Add the crumbled turkey sausage and cook, breaking it up with a wooden spoon, for 6 to 8 minutes until browned and cooked through. Transfer to a plate lined with paper towels and drain any excess fat.
Getting good browning on the sausage adds a lot of flavour to the finished casserole, so resist the urge to rush this step.
4
In the same pan, reduce the heat to medium and add the diced onion and red bell pepper. Cook for 4 to 5 minutes until softened, then add the garlic and the white parts of the spring onions. Cook for another minute until fragrant. Add the baby spinach and stir until just wilted, about 1 minute. Season with a little salt and pepper, then remove from the heat.
5
In a large mixing bowl, whisk together the whole eggs, egg whites, and almond milk until fully combined. Add the smoked paprika, cumin, oregano, remaining salt, and remaining black pepper and whisk again until smooth.
Whisking the eggs thoroughly incorporates air, which gives the casserole a slightly lighter, fluffier texture once baked.
6
Scatter the roasted sweet potato cubes evenly across the base of the prepared baking dish. Spread the cooked turkey sausage over the top, then spoon the vegetable mixture evenly over the sausage layer. Sprinkle half the grated cheddar across the top of the vegetables.
7
Pour the seasoned egg mixture slowly and evenly over all the layers, allowing it to settle down through the filling. Gently press the filling down with a spatula to ensure everything is submerged. Scatter the remaining cheddar evenly over the surface.
If assembling ahead, cover tightly with plastic wrap or a baking dish lid at this point and refrigerate overnight. Remove from the fridge 15 minutes before baking.
8
Bake uncovered at 180 degrees Celsius fan (200 standard, 400 Fahrenheit) for 35 to 40 minutes until the egg is fully set in the centre, the edges are golden, and the top is lightly browned. A knife inserted into the centre should come out clean.
If the top is browning too quickly before the centre is set, loosely tent a piece of foil over the dish for the last 10 minutes.
9
Remove from the oven and allow the casserole to rest for 8 to 10 minutes before slicing. This resting time helps the squares hold their shape cleanly when you cut them. Scatter the green tops of the spring onions and the fresh parsley over the top before serving.

Nutrition per serving

278kcal

Calories

28g

Protein

16g

Carbs

11g

Fat

Fibre

Sugar

480mg

Sodium

Pro Tips

✓
Use freshly grated cheese rather than pre-shredded. Pre-shredded cheese contains anti-caking agents that stop it melting as smoothly.
✓
Sweet potato cubes should be no larger than 1cm so they cook through evenly during the bake.
✓
Let the assembled casserole sit uncovered in the refrigerator for at least 30 minutes before baking if you are not doing an overnight rest. This allows the egg mixture to soak into the filling.
✓
For the cleanest slices at a brunch, use a sharp serrated knife and wipe it between cuts.
✓
Roasting the sweet potato before assembling prevents a watery casserole. Raw potato releases too much moisture during baking.
✓
Double the recipe and use two 9x13 dishes if you are feeding more than 20 people. Both can bake side by side on different oven racks.

Frequently Asked Questions

Can I make this breakfast casserole the night before a big brunch?↓

Absolutely, and it is actually better for it. Assemble the casserole completely, cover tightly and refrigerate overnight for up to 12 hours. The next morning, remove it from the fridge while the oven heats up, then bake as directed. The flavours meld beautifully and the egg mixture soaks into every layer.

How many people does this breakfast casserole serve?↓

This recipe comfortably serves 12 people with generous portions. If you are serving it alongside fruit, salad or other brunch dishes, you could stretch it to 14 to 16 lighter servings.

Can I use regular potatoes instead of sweet potato?↓

Yes. Diced Yukon gold or red potatoes work well. Par-boil or roast them first just as you would the sweet potato. The flavour will be more neutral and the fibre content slightly lower, but the structure of the casserole stays exactly the same.

Is this casserole gluten free?↓

Yes, this recipe contains no gluten-containing ingredients. Always check the labelling on your turkey sausage, as some brands include breadcrumbs or fillers that contain gluten.

How do I know when the casserole is fully cooked?↓

The casserole is done when the egg is completely set in the centre with no jiggling when you gently shake the dish. A small knife or skewer inserted into the middle should come out clean, with no raw egg on it. If the edges are set but the centre is still wet, give it another 5 minutes and check again.

Can I freeze this breakfast casserole?↓

Yes. Bake fully, cool completely, then slice into individual portions and wrap each one tightly. Freeze for up to 2 months. Reheat portions in the microwave for 2 to 3 minutes from frozen, or thaw overnight in the fridge and reheat in a 160 degree oven for 12 to 15 minutes.

Variations

•
Mediterranean Style
Swap the turkey sausage for diced chicken breast, add sun-dried tomatoes, kalamata olives, and crumbled low fat feta instead of cheddar. Season with dried thyme and a pinch of chilli flakes for a bright, herb-forward casserole.
•
Tex-Mex Brunch Bake
Use chicken or turkey chorizo in place of plain turkey sausage. Add black beans, sweetcorn, and diced green chillies to the vegetable layer. Top with reduced fat Monterey Jack or pepper jack cheese and serve with salsa and plain Greek yoghurt on the side.
•
Fully Vegetarian
Omit the turkey sausage entirely and double the vegetables. Add sliced mushrooms, courgette, and a cup of cooked brown lentils for extra plant-based protein. The lentils hold their structure well and add a hearty, meaty quality to each slice.
•
Dairy Free Version
Replace the cheddar with a plant-based melting cheese or simply omit it and add nutritional yeast stirred into the egg mixture for a cheesy, savoury flavour. Use unsweetened oat milk or almond milk in the egg custard.

Substitutions

•
Turkey sausage → Chicken sausage or lean ground turkey (Season ground turkey with fennel seeds, garlic powder, and smoked paprika if using plain ground turkey to mimic sausage flavour.)
•
Unsweetened almond milk → Low fat dairy milk or unsweetened oat milk (Any unsweetened plant milk or low fat dairy milk works in equal quantities. Avoid sweetened varieties.)
•
Reduced fat cheddar → Reduced fat Gruyere or part-skim mozzarella (Gruyere adds a nuttier depth of flavour. Mozzarella gives a milder, stretchier result.)
•
Sweet potato → Diced butternut squash or Yukon gold potato (Both need the same par-roasting step. Butternut squash keeps the natural sweetness similar to sweet potato.)
•
Baby spinach → Kale or Swiss chard (Remove tough stems and chop finely. Kale and chard take an extra minute or two to wilt fully in the pan.)

🧊 Storage

Store leftover casserole in an airtight container in the refrigerator for up to 4 days. Reheat individual portions in the microwave for 1.5 to 2 minutes, or cover with foil and warm in a 160 degree Celsius oven for 15 minutes. The casserole can also be frozen in individual portions for up to 2 months.

📅 Make Ahead

Assemble the entire casserole up to 12 hours ahead, cover tightly with plastic wrap, and refrigerate. On the morning of your brunch, remove the dish from the fridge while the oven preheats and allow it to sit at room temperature for 15 minutes. Bake as directed. This overnight rest actually improves the texture as the egg mixture fully saturates all the layers.