Ingredients
Amounts are for the recipe. Sizes, times and temperatures in the method are not scaled.
Caramel
Custard
Sponge
Amounts worked out from the other system are rounded.
Method
Caramel. Melt the granulated sugar (200 g1 cup) in a dry, heavy pan over medium heat, swirling rather than stirring. At deep amber, pour it at once into a 12-cup bundt pan and tilt to coat the bottom and partway up the sides. It sets in seconds.
Custard. Warm the milk (700 ml3 cups) to lukewarm. Beat the large eggs (8) with the granulated sugar (130 g⅔ cup) gently, just until the sugar dissolves. Stream in the warm milk, whisking gently, and add the vanilla (1 tsp). Pour carefully over the caramel.
Sponge. Whip the 3 egg whites with the pinch of salt to soft peaks, add the granulated sugar (70 g⅓ cup) and whip to stiff peaks. Whisk the 5 yolks with the oil (30 ml2 tbsp), then fold them into the whites in three or four strokes. Sift the flour (70 g½ cup + 1 tbsp) over and fold just until no dry pockets remain. Streaks of foam are fine; don't smooth it out.
Top. Spoon the sponge over the custard in rough dollops. Don't pour it and don't level it.
Bake at 175°C (350°F), with no water bath, for 45 to 55 minutes, with a sheet pan underneath to catch drips. The sponge should be golden and firm to the touch. The custard underneath will still wobble like jello.
Cool and flip. Cool completely in the pan at room temperature, at least 2 hours, then refrigerate overnight. Run a knife around the edges and the center tube, set a platter on top and flip in one motion. Cut into slices.
Notes
- The layers swap places in the oven. Flipped out, the caramel crowns the flan, with the sponge underneath.
- Wet caramel. Add 3 tbsp water to the sugar, stir until dissolved, then boil without stirring.
- Overflow is the main risk. The foam takes more room than a poured batter. In a 10-cup bundt, hold back about 1 cup of the custard.
- Sponge. The large, shaggy holes come from a coarse egg foam with little flour and no baking powder, folded roughly.
- Flan. It gets some holes too without a water bath. For a smoother flan, use a water bath for the first 30 minutes only.
- There are 13 eggs in all. Pastured eggs give the deepest yellow.