Peel, core and slice apples into thin slices and place them in a bowl. Sprinkle the slices with the juice of one lemon and toss gently to prevent the slices from turning brown.
In a medium bowl, mix the flour, baking powder, sugar, eggs, butter and milk, blending well. Fold apple slices into batter.
Pour batter into a buttered 10-inch baking pan. Bake in 350-degree oven for 60 minutes. Check doneness with toothpick. Dust top of cooled cake with powdered sugar and garnish with fresh sliced apples and a sprig of rosemary. Serve warm with heavy whipping cream.