Rum Apple Cake

Preheat the oven to 300u0b0 F. Butter an 8-inch spring form cake pan with a removable base.
Peel, quarter, and core the apples. Cut 2 of the quarters into thin slices, toss in a bowl with a splash of lemon juice and set aside.
Slice the remaining apple quarters more thickly into cubes. In another bowl, toss with a splash of lemon juice. Sprinkle with 1 tablespoon maple sugar and set aside for 10 minutes.
Cream the butter and remaining sugar together until light and fluffy. Beat in the egg yolks and then incorporate the ground almonds and baking powder, working the mixture as little as possible to keep it light. Transfer the mixture to a large bowl.
In another bowl, beat the egg whites until stiff. Fold half into the cake mixture and then fold in the remainder. Add the rum, and any juice given out by the thicker chunks of apple. Gently fold the chunks into the mixture. Transfer to the prepared cake pan and smooth the surface.
Drain the reserved finely sliced apple and arrange on top of the cake, fanning out the apple slices in a circle. Bake in the oven for 1 hour and 15 minutes, or until golden and a skewer comes out clean.
Run a knife around the edge of the cake and leave it to cool for several hours before serving. If you'd like to serve it warm you may reheat it. It keeps well in a covered container and can be reheated to serve warm later. Dust the cake with confectioner's sugar and serve with whipped cream or ice cream.