Heat oven to 350. Lightly spray 24 muffin cups w/ cooking spray. In lg bowl, make cake mix as directed on box. Stir in peanut butter chips. Spoon mix evenly into cups, 3/4 full. Bake as directed on box for cupcakes.
In lg bowl, beat cream cheese, butter and peanut butter until creamy. Beat in powdered sugar and vanilla until smooth.
Frost cooled cupcakes. Drizzle each cupcake w/ heated fudge sauce. Refrigerate at least 1 hr to set chocolate.