BROWNIE CRUSTHeat oven to 350°F. Grease 9-inch springform pan with butter. Stir together butter, sugar and vanilla in large bowl with spoon or wire whisk. Add eggs; stir until well blended. Stir in flour, cocoa, baking powder and salt; blend well. Spread in prepared pan. Bake 25 to 30 minutes or until brownie begins to pull away from side of pan. (While brownie layer is cooking, make cheesecake layer.) Immediately after removing brownie from oven, sprinkle milk chocolate chips, peanut butter chips and peanut butter cups over brownie surface. Spoon cheesecake mixture over chips. Turn oven down to 325°F. Double-wrap springform pan with aluminum foil to prevent water seeping inches. Place springform pan into a larger baking pan. Pour hot water into the larger pan so that the water comes 1 inch up the sides of the springform pan. Bake at 325°F for 1 1/2 hours, or until firm and lightly golden. Remove from the oven and allow to cool on a wire rack for one hour. Run a knife along the edge of the cake to loosen it from the pan somewhat. Refrigerate for at least 4 hours before decorating. CHEESECAKE LAYERBeat cream cheese in bowl of electric mixer until smooth. Add eggs, one at a time, beating well after each addition. Add sugar, peanut butter and cream; mix until smooth. Stir in vanilla. Pour filling into prepared brownie crust. DECORATIONRemove cake from pan and set on plate. Bring whipping cream to boil in a small saucepan. Remove from heat and add semi-sweet and peanut butter chips. Stir, stir, stir until melted and smooth. Drizzle over cake and then add peanut butter cup halves around the edge of the cake.