We're not afraid to call this our Best Chocolate Brownie recipe ever. The batter and the creamy frosting are full of HERSHEY'S Cocoa — look at that fudgy, dreamy texture! Boxed individually or featured in a bakery case, they'll be tough for your guests to resist.
Heat convection oven to 300°F (standard oven: 350°F). Lightly spray one 18x26-inch full sheet pan with vegetable cooking spray. Place parchment paper on prepared pan.
Mix together butter, sugar and vanilla in 20 qt. bowl of mixer fitted with paddle attachment until creamy. Add eggs, one at a time, blending after each addition. Blend HERSHEY'S Cocoa, flour, baking powder and salt in large bowl. Gradually add to butter mixture, mixing until well blended. Stir in walnuts, if desired. Pour batter into prepared pan.
Bake 30 to 40 minutes* or until brownies begin to pull away from sides of pan. Cool completely in pan on wire rack. Cut into 2x3-inch bars.
Step 3: If using convection oven, rotate sheet pan one-half turn (180°) after 15 minutes of baking.