This apple cinnamon upside-down cake recipe is a fun twist on the classic cake. The cake is moist, fluffy, and packed with apple and cinnamon flavors. The topping is made with sliced apples, brown sugar, and butter. To make this cake, you'll need flour, sugar, baking powder, salt, cinnamon, eggs, oil, vanilla extract, apples, brown sugar, and butter. Mix the dry ingredients in one bowl and the wet ingredients in another. Then, combine the two mixtures and fold in the chopped apples. Arrange the sliced apples in the bottom of a greased baking pan and sprinkle the brown sugar and butter over the apples. Pour the batter over the topping and bake for 35-40 minutes. Let the cake cool before flipping it onto a serving plate. Serve warm with a dollop of whipped cream.