Almond meal (also called "almond flour") and almond extract add great flavor to this cake, which is packed with fresh blueberries. This cake makes a nice, not-too-sweet addition to a Sunday brunch. Be sure to use fresh blueberries; frozen berries will contribute too much liquid to the cake.
Position a rack in the lower third of the oven and preheat to 325 degrees F. Butter the sides of a 9-inch square baking pan and line the bottom with a piece of parchment or wax paper. Set aside.
Place the eggs and the vanilla and almond extracts in the bowl of a heavy-duty mixer and beat on medium speed for 1 minute. Gradually add the sugar, increasing the speed of the mixer to high. Beat until the eggs have tripled in volume and become thick and pale-colored, about 8 minutes.
Meanwhile, whisk together the flour, baking powder, and salt. When the eggs have reached their desired volume, remove the bowl from the mixer stand and gently fold the flour mixture into the eggs. Add the almond meal and butter, folding them gently into the batter and taking care not to deflate it.
Transfer the batter to the prepared pan. Spread the blueberries over the top in a single layer. Bake until the cake is set and has begun to pull away from the sides of the pan, about 45 minutes. Transfer the pan to a wire rack and let the cake cool before serving.