1. Heat oven to 350°F. Grease and flour 13x9-inch baking pan.**
2. Beat butter and sugar in large bowl; add eggs and vanilla, beating well. Stir together buttermilk and food color. Stir together flour, cocoa and salt; add alternately to butter mixture with buttermilk mixture, mixing well. Stir in baking soda and vinegar. Pour into prepared pan.
3. Bake 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool completely in pan on wire rack. Frost; garnish with chocolate chips, if desired. About 15 servings.
* To sour milk: Use 1 tablespoon white vinegar plus milk to equal 1 cup.
VARIATION: For heart shapes: Using open-topped heart-shaped cookie cutter (at least 1-1/2 inches deep and 3-inches wide), cut cake into 12 hearts. Frost and decorate as directed.
**Cake can also be baked in two greased and floured 9-inch round baking pans. Bake at 350°F for 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool 10 minutes; remove from pans. Cool completely. Frost as desired.
HERSHEY'S RED VELVET CUPCAKES: Line about 28 muffin cups (2-1/2 inches in diameter) with paper or foil baking cups. Prepare batter as above; fill each muffin cup about 1/2 full with batter. Bake at 350°F about 20 minutes or until wooden pick inserted in centers comes out clean. Cool completely in pan on wire rack. Frost as desired. About 28 cupcakes.