Line a muffin tin with paper liners (standard or mini, depending on your preference).
Melt half of the chocolate chips in the microwave or a double boiler, stirring until smooth.
Spoon 1–2 teaspoons of melted chocolate into the bottom of each muffin liner and spread to cover the base. Freeze for 10 minutes.
In a bowl, mix peanut butter, powdered sugar, and vanilla extract until smooth and creamy.
Remove the muffin tin from the freezer and add a spoonful of peanut butter mixture on top of the hardened chocolate. Smooth it into an even layer.
Melt the remaining chocolate and spoon it over the peanut butter layer, spreading it to fully cover.
Freeze for 15 minutes or until firm.
Store in the refrigerator for up to 1 week or freezer for up to 2 months. Enjoy chilled or at room temperature.