Melt butter and peanut butter in microwave for 1 minute. Stir until blended.
Add powdered sugar and vanilla. Mix well, then freeze for 15 minutes. Grab a small ball of PB mixture, roll into a ball and then flatten. Set aside.
Melt chocolate in a pot on low heat until smooth (stirring the entire time). Pour 1 - 2 tbsp of melted chocolate into a cupcake liner in a muffin tin. Add the rounded, flattened peanut butter and top with 1 - 2 more tbsp melted chocolate. Help flatten chocolate by lightly banging on counter.
Refrigerate 10 minutes or until your chocolate has set. Decorate with extra drizzled chocolate, sprinkles or any other toppings.