Preparation - Combine the melted butter, sugar, brown sugar, egg and vanilla in a bowl. Stir until smooth and well blended. Mix the flour, baking powder and 1/4 tsp. cinnamon together. Add to the butter/sugar mixture. Stir in the chopped apples and walnuts. Spread the mixture in a greased 8" square baking pan. Mix the cinnamon and sugar together. Sprinkle the mixture over the batter. Bake in a preheated oven at 350º for 30 minutes. Cool in the pan, on a wire rack, then cut into squares.