I found a version of a chestnut cake like this in an old Gourmet magazine, and this acorn cake recipe is a riff off that. These are lovely done in a 9-inch springform pan, but are equally good in buttered ramekins. Be sure to use a small circle of parchment paper on the bottom of the ramekin, and butter both sides. This will help you get the little cakes out easier. Oh, and don’t forget they rise, so don’t fill them too high.
Grease the springform pan or ramekins. Preheat oven to 350°F.
Mix the acorn flour, wheat flour, baking soda and powder and salt in a bowl. In the bowl of a stand mixer, or in another large bowl, beat the egg yolks, oil, honey and 2 tablespoons of sugar together until it looks like caramel. Mix in the dry ingredients.
In another bowl, add the egg whites and just a pinch of salt and beat into soft peaks. Add the remaining sugar and beat a bit more, so the whites are reaching the firm peak stage.
Fold this into the dough a little at a time gently. Pour, or really gently place, the dough into the ramekins (remember they will rise!) or the springform pan. Using a rubber spatula flatten out the top and place in the oven as fast as you can.
Bake for about 30 minutes. After 20 minutes, watch for burning, as acorn flour browns faster than chestnut flour. Remove from the oven, let rest 5 minutes, then turn out onto a rack to cool.
When they have cooled for a good 15-20 minutes or so, dust with the confectioner’s sugar.