Cupcakes:

1 1/4 c. flour
1 1/2 tsp. baking powder
1/2 c. smooth peanut butter
1/2 stick soft butter
1/2 c. packed brown sugar
1 large egg
1/2 tsp. vanilla
2/3 c. milk

Whisk together flour and baking powder; set aside. Beat together peanut butter, butter and brown sugar. Add egg and vanilla; beat until fluffy. Add flour mixture and milk alternatively, beginning and ending with flour, until just combined. Divide batter among lined muffin cups (each cup about 2/3 full).

Bake at 350°F for 18-20 minutes. Let cool and frost with Milk Chocolate Icing.

Milk Chocolate Frosting:

1/3 c. heavy cream
4 oz. milk chocolate
1/3 c. chopped nuts

Bring cream to a boil in small saucepan; pour over chocolate in small bowl. Let stand 1 minute, then whisk until smooth. To thicken icing to spreading consistency, spread on metal baking sheet and chill until thick and glossy (about 5 minutes). Scrape icing back into bowl and stir until smooth. Spread onto cupcakes and sprinkle with peanuts.