In a large bowl, combine the dry ingredients. Cut in shortening until the mixture resembles coarse crumbs. Store in an airtight container in the refrigerator or freezer for up to 3 months. Yield: about 4 batches (about 11 cups total).

To prepare brownies: In a large bowl, combine eggs, vanilla and 2-1/2 cups brownie mix until blended (batter will be stiff). Stir in nuts if desired.

Spread into a greased 8-in. square baking pan. Bake at 350° for 20-25 minutes or until a toothpick inserted near the center comes out clean. Cool on a wire rack. Cut into bars. Yield: 16 brownies per batch. Editor's Note: Contents of brownie mix may settle during storage. When preparing recipe, spoon mix into measuring cup.