Step 1

Heat oven to 350°F.

Step 2

Prepare brownie batter as directed on package; stir in 1/4 cup nuts. Pour into 13x9-inch pan sprayed with cooking spray. Beat cream cheese, 1/4 cup peanut butter, sugar, milk and egg yolk in bowl with mixer until blended. Spoon mixture evenly over brownie batter.

Step 3

Bake 25 to 30 min. or until toothpick inserted in center comes out with fudgy crumbs. Cool completely in pan.

Step 4

Blend frosting and remaining peanut butter in bowl. Spread over cooled brownies; sprinkle with remaining nuts.