HEAT oven to 350°F. Coat bottom of an 8-inch round cake pan lightly with no-stick cooking spray. PREPARE brownie mix as directed on package using oil, water and egg. Stir in almond extract, peanut butter and peanuts until blended. Spread batter evenly into prepared pan. BAKE 40 to 42 minutes or until a toothpick inserted in the center comes out clean. Cool completely in pan. Place cake on serving platter. Stir topping until smooth. Spread over cake, covering top and sides. Place the tip of a frosting knife at the center of cake, pulling the knife toward the outer edge in a slight arc. Turn cake a notch counter clockwise. Repeat knife pull as a pattern forms all around the cake. Garnish center of cake with a fresh mint sprig, if desired.