Line muffin cups with paper bake cups. Spread about 1 tablespoon crushed crackers in each cup. Set aside. Beat cream cheese till smooth. Add sugar and vanilla. Beat till fluffy. Beat in milk. Add eggs, beating just till combined. Divide mixture in half.
Gradually stir peanut butter into half of the cheese mixture. Stir chocolate into the remaining cheese mixture. Spread 2 tablespoons of the peanut butter mixture evenly over cracker crumbs in each muffin cup. Top each with 2 tablespoons of the chocolate mixture. Bake in a 325 degree oven for 20 to 25 minutes or till set. Cool on a wire rack. Chill. To serve, peel off paper cups and invert.