Heat oven to 375°F. Grease an 8- or 9-inch round cake pan with cooking spray and line with parchment paper. Reserve 1 tablespoon of brown sugar but add the rest of the sugar and the butter to a bowl. Beat until fluffy. Add eggs, beating in 1 after the other. Add flour, baking powder and cinnamon and stir gently until just combined. Stir in the apples and the apple juice. Spoon batter into the pan—it will seem like a lot of apples, but fear not! Sprinkle the top with reserved tablespoon of brown sugar. Bake for about 45 minutes, or until cooked through. Let cool for at least 1 hour before serving. Serve warm, room temperature or cold. This makes a great breakfast or dessert.