Line a mini muffin tin with cupcake liners. In a medium-sized mixing bowl, combine peanut butter, powdered sugar, and vanilla extract. Whip with an electric hand mixer until smooth.

Melt the chocolate either in a double boiler or by microwaving in short increments, stirring every 30 seconds. Add a teaspoon of melted chocolate to the bottom of each mini muffin cup, followed by a teaspoon of the peanut butter mixture. Add another teaspoon of the melted chocolate and spread it evenly over the peanut butter layer. Freeze for 15 minutes. Serve at room temperature.