Cream sugar and butter by beating with an electric mixer in a large bowl until thoroughly blended.
Add eggs and almond extract; mix until blended. Stir together flour and baking powder. Add to creamed mixture; stir together just to blend, but do not over-mix.
Spread half of batter evenly in a greased 9 x 13-inch (23 x 33 cm) baking dish. Peel, core and thinly slice apples; lay slices on top of batter.
Sprinkle apples with a little lemon juice, if desired. Using two spoons, drop remaining batter in small spoonfuls over apples. The apples don’t need to be completely covered as batter will spread as it bakes. Sprinkle almonds on top.
Bake in a preheated 325°F (165°C) oven until firm to the touch and lightly browned, about 40 minutes