Using a 2 ½ inch muffin pan, line eight muffin cups with paper bake cups; set pan aside. We used much smaller paper bake cups to double the final piece count and make them bite size.
In a small saucepan, heat the semisweet and milk chocolate pieces over low heat until melted.
Remove saucepan from heat.
In a second small saucepan, heat the peanut butter, butter, and vanilla over low heat, stirring constantly until melted.
Once melted, add the confectioners sugar and stir. Remove from heat.
If you are using the larger paper bake cups pour about 1 tablespoon melted chocolate into each paper bake cup; chill about 5 minutes until chocolate is firm.
Pour about 1 tablespoon melted peanut butter over the firm chocolate in each paper bake cup; chill about 5 minutes more until peanut butter is firm.
Pour the remaining melted chocolate evenly over the peanut butter layer in each paper bake cup.
Sprinkle each with chopped peanuts.
Chill candy about 10 minutes or until firm.
Store tightly covered in the refrigerator. To serve allow cups to stand at room temperature for 5-10 minutes.