Adapted from this classic White Texas Sheet Cake recipe.
If you're not opposed to using sugar {like 2 - 4 cups of sugar!}, have a look at the frosting in the original recipe I adapted from -- you can easily use non-dairy ingredients to get that frosting. I made mine the way it is to cut down on the sugar and I actually really loved the flavor and texture I ended up with, but giving the more traditional alternative option here as well in case anyone prefers that.