In small bowl, beat egg whites with electric mixer on medium speed until stiff peaks form; set aside. In large bowl, beat egg yolks and brown sugar on medium speed until mixture is light in color and thickens. Add peanut butter and corn syrup; beat until blended. Beat in milk and vanilla gradually on low speed. Gently stir egg whites into peanut butter mixture until blended; spread over chocolate chips and peanuts.