1. Preheat oven to 350°. Melt 1/4 cup butter in a lightly greased 9-inch round cake pan (with sides that are at least 2 inches high) over low heat. Remove from heat. Sprinkle with brown sugar; drizzle honey over brown sugar. Arrange apple slices in concentric circles over brown sugar mixture, overlapping as needed; sprinkle with blackberries.
2. Beat granulated sugar and remaining 1/2 cup butter at medium speed with an electric mixer until blended. Add eggs, 1 at a time, beating until blended after each addition.
3. Stir together flour and baking powder. Add flour mixture to sugar mixture alternately with milk, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Stir in vanilla. Spoon batter over blackberries in pan.
4. Bake at 350° for 45 to 50 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack 10 minutes. Carefully run a knife around edge of cake to loosen. Invert cake onto a serving plate, spooning any topping in pan over cake.
*1 cup fresh or frozen cranberries may be substituted.