BATTER:

1 1/4 c. all-purpose flour
1 c. firmly packed light brown sugar
3/4 c. milk
1/4 c. peanut butter
1 egg
1 tbsp. butter, softened
1 tbsp. vegetable oil
1 tsp. vanilla extract
1 1/2 tsp. baking powder
1/2 tsp. salt
1/2 c. semi-sweet chocolate chips

Preheat oven to 350 degrees. Combine all ingredients for batter in blender. Cover and blend at high speed about 45 seconds, stopping motor once or twice to scrape down sides. Pour into muffin tins fitted with paper cupcake liners, filling each about 2/3 full. Bake 25-30 minutes until toothpick comes out clean. Cool completely. Spread with frosting. If desired, garnish with peanuts.

FROSTING:

3 c. powdered sugar
1/4 c. (1/2 stick) butter, softened
1/4 c. cocoa
1/4 c. peanut butter
1 tsp. vanilla extract
3/4 tbsp. milk
2/3 c. chopped honey-roasted peanuts (optional)

Combine all ingredients in bowl and beat until smooth and spreadable.