French onion financiers are a savory twist on the classic French tea cake, swapping sugar for deeply caramelized onions and Gruyère cheese. These small, buttery cakes have a nutty flavor from browned butter (beurre noisette) and a delightfully moist, tender crumb with a slightly crisp edge. They are perfect as an elegant appetizer, a lunchbox treat, or a sophisticated addition to a cheese board.
Ingredients
- 1/2 cup (1 stick / 113 g) unsalted butter, plus extra for the pan
- 2 large yellow onions (about 1 lb / 450 g), thinly sliced
- 1 tablespoon olive oil
- 1/2 teaspoon salt, plus more to taste
- 1/4 teaspoon black pepper
- 1/2 cup (60 g) all-purpose flour
- 1/2 cup (50 g) almond flour (or finely ground almonds)
- 1/2 teaspoon baking powder
- 3 large egg whites, at room temperature
- 1/2 cup (50 g) finely grated Gruyère cheese (about 2 oz / 55 g)
- 1 teaspoon fresh thyme leaves (optional)
Instructions
- Preheat your oven to 375°F (190°C). Generously butter a 12-cup mini muffin pan (or use silicone molds).
- In a small saucepan, melt the butter over medium heat. Continue cooking, swirling occasionally, until the butter turns a deep golden brown and smells nutty, about 5–7 minutes. Watch carefully; it can burn quickly. Remove from heat and let cool slightly.
- While the butter browns, heat the olive oil in a large skillet over medium-low heat. Add the sliced onions, salt, and pepper. Cook, stirring occasionally, until the onions are very soft and deeply caramelized, about 20–25 minutes. They should be a rich golden brown and reduced significantly. If they start to stick, add a splash of water or broth. Set aside to cool slightly.
- In a medium bowl, whisk together the all-purpose flour, almond flour, and baking powder.
- In a separate large bowl, whisk the egg whites until frothy but not stiff. Add the browned butter (it should be warm but not hot) and whisk to combine.
- Add the dry ingredients to the egg white mixture and stir until just combined. The batter will be thick.
- Fold in the caramelized onions, grated Gruyère, and thyme (if using). Mix until evenly distributed.
- Spoon the batter into the prepared muffin cups, filling each about 3/4 full.
- Bake for 15–18 minutes, until the financiers are golden brown and a toothpick inserted into the center comes out clean.
- Let cool in the pan for 5 minutes, then transfer to a wire rack. Serve warm or at room temperature.
Tips
- Caramelize onions properly: Don’t rush this step. Low and slow is key for sweet, jammy onions. If they brown too quickly, lower the heat.
- Brown butter carefully: The butter will foam and then turn golden. Remove from heat as soon as it smells nutty and has a deep amber color. Burnt butter will taste bitter.
- Use room-temperature egg whites: They incorporate more air and give a lighter crumb. If you’re in a hurry, place the eggs in a bowl of warm water for 5 minutes.
- Substitutions: Swap Gruyère for Swiss, Emmental, or sharp cheddar. If you don’t have almond flour, use an equal amount of all-purpose flour, but the texture will be slightly less tender.
Serving Suggestions
Serve these financiers as an appetizer with a dollop of crème fraîche or a spoonful of onion jam. They pair beautifully with a crisp green salad, a bowl of tomato soup, or alongside roasted meats. They also make a delightful addition to a brunch spread or a picnic basket.
Variations
- Add bacon: Crumble 2–3 slices of cooked bacon into the batter for a smoky, savory twist.
- Herb swap: Replace thyme with rosemary, sage, or chives.
- Cheese change: Use blue cheese or goat cheese for a tangier flavor.
- Mini quiche style: Make a well in the center of each financier before baking and crack a tiny egg into it, then bake until the egg is set (160°F / 71°C for egg dishes).
Storage and Reheating
Store leftover financiers in an airtight container in the refrigerator for up to 4 days. To reheat, place them on a baking sheet and warm in a 350°F (175°C) oven for 5–7 minutes, or until heated through. They can also be frozen for up to 2 months; thaw overnight in the refrigerator and reheat as directed.
Frequently Asked Questions
Can I use whole eggs instead of egg whites? Yes, but the texture will be denser and less delicate. If using whole eggs, use 2 large eggs and whisk them lightly before adding.
Why are my financiers dry? Overbaking is the most common cause. Check them at the 15-minute mark. Also, ensure your almond flour is fresh; old almond flour can dry out baked goods.
Can I make these gluten-free? Yes, use a 1-to-1 gluten-free flour blend in place of all-purpose flour. The almond flour is already gluten-free.
Can I use pre-caramelized onions from a jar? Yes, but they may have added sugar or vinegar. Drain them well and pat dry before using. Adjust salt accordingly.
Can I make the batter ahead of time? You can prepare the batter and refrigerate it for up to 24 hours. Let it come to room temperature before baking, and add 2–3 minutes to the baking time.
What if I don’t have a mini muffin pan? Use a regular muffin pan and increase the baking time to 20–25 minutes. You’ll get about 6 standard-sized financiers.
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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes
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