A southern chocolate sheet cake, with a sugary chocolate icing. As much iced brownie as cake!
Mix dry ingredients in a large mixing bowl. Add wet ingredients and whisk well to combine. Add nuts if using. Pour into a greased jelly roll (15-inch) pan. Bake at 325F for 25 minutes, until a toothpick inserted in the center comes out clean. Cool completely before icing.
Combine butter, milk, and sugar. Bring to a gentle boil, stirring constantly. Add chocolate chips and vanilla. Keep over low heat and stir until chocolate chips are melted. Pour onto cake and let cool before serving.
I've cut the oil in half in this recipe, and it's a thin cake, so do not overbake. If your oven runs hot, check on the cake at 20 minutes.