Prepare mini muffin pans with liners (makes 64).
Mix peanut butter, butter, sugars & vanilla until well blended.
Crush 3/4 c. white chocolate M&M's (I used a food processor) and fold them into peanut butter mixture.
Press 1 Tbsp. mixture into each muffin cup.
Melt chocolate chips (half at a time) and top each cup with 1 tsp. white chocolate and one of the remaining M&M's.
Chill until firm. Store in refrigerator or freezer.