Microwave peanut butter for 30 seconds. Spread over crust. Beat cream cheese, sugar, and sour cream until smooth. Add eggs. Beat until combined. Stir in vanilla. Pour one cup of the mixture into a bowl and set aside. Pour remaining mixture onto crust. Microwave 1/4 cup hot fudge topping for 30 seconds. Fold into batter that was set aside. Spoon into pan, swirl with knife. Bake 55 - 65 minutes at 350º. Cool 10 minutes. Spread remaining hot fudge on top. Sprinkle with peanut butter cups. Refrigerate overnight.