Mix the remaining peanut butter with ⅛ teaspoon salt.
Spoon ½ tablespoon into each cup. If the peanut butter is thick, first flatten it out in your hand and then place it on top of the chocolate.
Top with another spoonful of chocolate fudge batter.
Freeze for about 2 hours, or until firm.
Enjoy! Store in the freezer.
Notes
A note about substitutions: You can substitute casein powder for the whey powder. For a vegan version, you can use a chocolate pea protein blend. Other vegan powders are chalkier, and wouldn't work well.