This chocolate sheet cake is a family favourite and the only chocolate cake recipe I've used for the past 20 years. It's a heavier, fudgy tasting cake that mixes up fast and easy. The baking time is less around 18 minutes til done. Be careful not to over bake. Check for doneness after 15 minutes. I bake in a convection, so it usually bakes a bit faster. For cupcakes, the baking time will be a bit less. About 13 minutes at 325'F. With fudge icing spread on top of the sheet cake, no one can resist the awesome chocolatey taste. And for those who prefer a sweeter icing, I use a buttercream frosting for the cupcakes to make them a bit more decorative.