1. Prepare CHOCOLATE CRUMB CRUST. Heat oven to 450°F.
2. Beat cream cheese, sugar, sour cream and vanilla in large bowl until smooth. Add flour, 1 tablespoon at a time, blending well. Add eggs; blend just until smooth. Place peppermint pattie pieces and milk in medium microwave-safe bowl. Microwave at MEDIUM (50%) 1 to 1-1/2 minutes or just until candy is melted and smooth when stirred. Add to cream cheese mixture, blending until smooth. Pour into prepared crust.
3. Bake 10 minutes. Reduce temperature to 250°F.; continue baking 40 to 45 minutes or until center appears set. Remove from oven to wire rack; with knife, loosen cake from side of pan. Cool completely; remove side of pan. Cover; refrigerate. Garnish with whipped cream, if desired. Cover; refrigerate leftovers. 10 to 12 servings.
CHOCOLATE CRUMB CRUST: Place 6 tablespoons butter or margarine in medium microwave-safe bowl. Microwave at MEDIUM (50%) 30 seconds or until melted. Stir in 1-1/2 cups finely crushed vanilla wafers (about 45 wafers, crushed), 6 tablespoons powdered sugar and 6 tablespoons HERSHEY'S Cocoa; blend well. Press mixture onto bottom and 1/2 to 1 inch up side of 9-inch springform pan.