For the cake, mix dry ingredients. Add wet ingredients. Mix with electric mixer on medium speed for about two minutes. Pour into a greased 9×11 pan or two round pans. Bake at 350 degrees for 25-30 minutes. Don’t overbake or the cake will be too dry!
You can also make cupcakes and bake them at 350 degrees for 20 minutes. The cupcakes will fall after they come out of the oven, but this is normal. Just fill up the indentation with more frosting.
For the frosting, place the butter in a large mixing bowl. Add 4 cups of sugar, then the juice and the zest. Beat until smooth and creamy. Gradually add the remaining sugar, 1 cup at a time, until icing is thick enough to be of good spreading consistency (I added about 6 cups total). Use and store at room temperature. (Don’t refrigerate and it will last in a covered container for about three days.)