Caramelized Onion and Gruyere Breakfast Quiche with a Almond Flour Crust
There is something genuinely magical about slow-cooked onions. Give them enough time in a pan with a little olive oil and they transform from sharp and pungent into something deeply golden, sweet, and utterly savoury. That flavour is the whole foundation of this caramelized onion and gruyere breakfast quiche, and it does most of the heavy lifting so you do not need to pile in excessive cream or butter to get something that tastes rich and satisfying.
Most traditional quiche recipes lean heavily on heavy double cream and a butter-laden pastry shell, which pushes the calorie count up fast. This version takes a smarter approach. The crust is made from almond flour, ground flaxseed, and a little olive oil, giving you a nutty, slightly crisp base that is naturally gluten-free and much higher in fibre than standard shortcrust. The custard filling swaps out heavy cream for a combination of whole eggs, extra egg whites, and low-fat milk. You still get that creamy, silky set texture, but with significantly more protein and far fewer calories per slice. Gruyere cheese stays in the recipe because its nutty, slightly earthy flavour is genuinely irreplaceable here. A smaller quantity of properly good Gruyere does more flavour work than a large pile of a milder cheese ever could.
The caramelized onions take about 35 to 40 minutes on a low heat, and that time investment is non-negotiable if you want the best result. Rushing them gives you softened onions with a faintly bitter edge. Going slow gives you that jammy, deeply golden sweetness that makes every bite of this quiche taste like something special. While the onions are doing their thing, you can prep the crust, whisk the custard, and get everything else ready. Fresh thyme leaves stirred through the filling add a herby, slightly floral note that pairs beautifully with both the onions and the cheese. A small handful of baby spinach folded into the base of the filling boosts the fibre and micronutrient content without changing the character of the dish at all.
This quiche is genuinely versatile. It works as a weekend brunch centrepiece, a meal-prep option you can slice and refrigerate for weekday breakfasts, or a light lunch alongside a simple green salad. Each slice delivers around 22 grams of protein, which is a meaningful contribution to your daily intake from a single breakfast portion. It reheats beautifully in the oven or a low microwave setting, and the flavours actually deepen a little overnight as the onion and Gruyere settle together. If you have never made a homemade quiche before, this is a great starting point. The almond flour crust is more forgiving than traditional pastry, no blind baking weights are needed, and the filling comes together in one bowl. It is the kind of recipe that looks and tastes impressive but rewards you with straightforward, stress-free cooking.
Ingredients
- 1.5 cups almond flour (blanched, finely ground)
- 2 tablespoons ground flaxseed
- 0.3 teaspoon fine sea salt (for the crust)
- 2 tablespoons olive oil (extra virgin, for the crust)
- 1 tablespoon cold water (add more a teaspoon at a time if needed)
- 3 large yellow onions (peeled and thinly sliced)
- 1 tablespoon olive oil (for caramelizing the onions)
- 0.5 teaspoon fine sea salt (for the onions)
- 1 teaspoon fresh thyme leaves (or 0.5 teaspoon dried thyme)
- 1 cup baby spinach (lightly packed, roughly chopped)
- 3 large whole eggs (free-range if possible)
- 3 large egg whites (free-range if possible)
- 0.8 cup low-fat milk (1% or semi-skimmed)
- 0.3 cup plain low-fat Greek yogurt (adds creaminess and protein)
- 0.5 teaspoon Dijon mustard
- 0.3 teaspoon black pepper (freshly ground)
- 0.3 teaspoon ground nutmeg
- 90 grams Gruyere cheese (finely grated, about 0.75 cup packed)
- 1 tablespoon fresh chives (finely chopped, for garnish)
Instructions
- 1
Start with the onions since they take the longest. Heat one tablespoon of olive oil in a wide, heavy-based pan over a medium-low heat. Add the sliced onions and 0.5 teaspoon of salt. Stir to coat, then cook slowly for 35 to 40 minutes, stirring every few minutes. The onions should gradually soften, turn golden, then deepen to a rich amber colour. If they start to catch on the bottom, add a small splash of water and stir. Once deeply caramelized, stir in the thyme leaves and remove from heat. Set aside to cool slightly.
Low and slow is the rule. Turning up the heat to speed things up gives you browned but not truly caramelized onions. The difference in flavour is enormous.
- 2
Preheat your oven to 180 degrees Celsius (350 degrees Fahrenheit). Lightly grease a 9-inch pie dish or tart tin with a little olive oil.
- 3
Make the crust. In a medium bowl, combine the almond flour, ground flaxseed, and 0.25 teaspoon of salt. Add the two tablespoons of olive oil and one tablespoon of cold water. Mix until the dough comes together into a soft, slightly sticky ball. If it feels too dry and crumbly, add water one teaspoon at a time.
Almond flour dough is much softer than regular pastry. Do not worry about overworking it.
- 4
Press the dough evenly across the base and up the sides of the prepared pie dish using your fingers and the back of a spoon. Aim for an even thickness of about 4 to 5 millimetres. Prick the base a few times with a fork, then bake blind for 10 to 12 minutes until lightly golden at the edges. Remove and allow to cool for 5 minutes.
No need for baking beans or parchment here. The almond flour crust holds its shape without them.
- 5
While the crust cools, make the custard filling. In a large mixing bowl, whisk together the whole eggs, egg whites, low-fat milk, Greek yogurt, Dijon mustard, black pepper, and ground nutmeg until smooth and well combined.
The Greek yogurt adds a subtle tang and extra protein. It blends in completely once baked.
- 6
Scatter the chopped baby spinach evenly across the base of the pre-baked crust. Spoon the caramelized onions over the spinach in an even layer. Sprinkle two thirds of the grated Gruyere over the onions.
- 7
Carefully pour the egg custard mixture over the filling, letting it settle down through the onions and cheese. Scatter the remaining Gruyere over the top.
Pour slowly from the centre outward to avoid disturbing the layered fillings.
- 8
Bake at 180 degrees Celsius for 30 to 35 minutes until the custard is just set in the centre with a very slight wobble. The top should be lightly golden. If the crust edges are browning too fast, loosely cover them with a strip of foil.
The quiche firms up as it cools. Pulling it from the oven when there is still a tiny wobble in the centre means it will not be rubbery.
- 9
Allow the quiche to rest for 10 minutes before slicing. This resting time helps the custard fully set and makes clean slices much easier. Scatter fresh chives over the top before serving.
Nutrition per serving
318kcal
Calories
22g
Protein
12g
Carbs
21g
Fat
4g
Fibre
5g
Sugar
390mg
Sodium
Pro Tips
- ✓
Grate the Gruyere yourself from a block rather than buying pre-grated. Pre-grated cheese often contains anti-caking agents that affect how it melts.
- ✓
Room temperature eggs make for a smoother, lump-free custard. Take them out of the fridge about 20 minutes before you start.
- ✓
You can caramelize the onions up to three days ahead and store them in an airtight container in the fridge. This makes the actual quiche assembly very quick.
- ✓
If you want a deeper golden top on the quiche, switch the oven to a grill setting for the final two minutes of cooking. Watch it carefully.
- ✓
Letting the quiche cool completely before slicing and storing makes it much easier to portion neatly for meal prep.
Frequently Asked Questions
Variations
- •
Turkey Bacon and Gruyere Quiche
Cook 4 slices of turkey bacon until crispy, crumble, and layer with the caramelized onions before adding the custard. The smoky, salty turkey bacon adds another layer of flavour and extra protein.
- •
Mushroom and Gruyere Quiche
Saute 150 grams of sliced chestnut mushrooms in a little olive oil until golden and most of their moisture has evaporated. Add them alongside the caramelized onions for an earthy, deeply savoury filling.
- •
Crustless Caramelized Onion and Gruyere Quiche
Skip the almond flour crust entirely and pour the filling directly into a well-greased pie dish. This reduces calories and prep time further, and the result is more like a frittata. Bake at the same temperature but check for doneness a few minutes earlier.
- •
Roasted Red Pepper and Gruyere Quiche
Add two roasted red peppers, sliced, to the filling alongside the caramelized onions. Their sweetness echoes the onions and adds a beautiful colour contrast. You can use jarred roasted peppers drained well to save time.
Substitutions
- •Almond flour → Oat flour (Use the same quantity. The crust will not be gluten-free with oat flour unless certified gluten-free oats are used. The texture will be slightly softer.)
- •Gruyere cheese → Mature Comte or aged cheddar (Comte is the closest in flavour. Aged cheddar works well and is widely available. Use the same quantity.)
- •Low-fat milk → Unsweetened oat milk or almond milk (Use the same quantity. The custard will be slightly less rich but still sets well. Good option for dairy-light preferences.)
- •Plain low-fat Greek yogurt → Low-fat sour cream or low-fat creme fraiche (Either works well and gives a very similar creamy texture and slight tang.)
- •Yellow onions → White onions or shallots (White onions caramelize almost identically to yellow. Shallots caramelize faster and give a slightly sweeter, more delicate result.)
- •Fresh thyme → Fresh rosemary or dried herbes de Provence (Use half the quantity of rosemary as it has a stronger flavour. Herbes de Provence adds a lovely complexity.)
🧊 Storage
Cool the quiche completely before storing. Cover the dish tightly with clingfilm or transfer individual slices to an airtight container. Refrigerate for up to 4 days. To reheat, place slices in a 160 degree Celsius oven for 8 to 10 minutes or microwave on medium power for 90 seconds.
📅 Make Ahead
The caramelized onions can be made up to 3 days ahead and stored in the fridge. The entire quiche can be baked a day in advance and refrigerated overnight. It slices more cleanly when fully cold, making it ideal for meal prep.
