Preheat the oven to 350˚F (180˚C). Grease a soufflé mold of approximately 2 quarts (8 cups or 2 liters).
Cut the flesh of 1 apple into cubes. These will be used for the dough. Using a mandoline, cut the rest of the apples into thin slices. Using the best looking ones first, arrange the apple slices in the bottom of the soufflé bowl in concentric circles, pressing down to ensure the cake batter won’t crawl into any crannies. Add the maple syrup and set aside.
In a bowl, mix the flour, baking powder, cinnamon and sea salt. In a second mixing bowl, beat the butter into a cream. Add the brown sugar and keep beating until fluffy. Add the aquafaba and beat until the mixture is soft and homogenous. Add the dry ingredients, alternating with some apple juice, until no more. Mix well. Add the apple cubes and fold in using a spatula. Spread the cake batter on top of the apple sliced in the soufflé bowl.
Place in the oven and bake for approximately 1 hour and 30 minutes, or until a toothpick inserted in the thickest part of the cake comes out clean. Let cool 15 minutes. Run the thin blade of a knife between the cake and the soufflé pan. Invert the cake onto a serving platter or a cake stand. Serve warm or room temperature. Serve with maple yogurt, some ice cream on the side, or simply as is. It makes for a great mid-morning snack, too! Bon appétit!
* If you plan on making your own juice, ensure you have a total of 7 apples.
Keywords: upside down cake, apple, maple