H-e-b Single Layer White Buttercream Cake

small white cake (water, sugar, enriched bleached wheat flour (wheat flour, reduced iron, niacin, thiamin mononitrate, riboflavin, folic acid), soybean oil, egg whites, palm oil, emulsifier blend (propylene glycol monoesters, mono & diglycerides, soy lecithin, BHT (preservative), citric acid), dextrose, skim milk, modified cornstarch, leavening (sodium aluminum phosphate, sodium bicarbonate), egg yolks, salt, soy protein, polysorbate 60, natural & artificial flavors, gum arabic, corn syrup solids, tetrasodium pyrophosphate, sodium propionate (preservative), calcium acetate, guar gum, potassium sorbate (preservative), xanthan gum), vanilla light 'n fluffy icing (sugar, vegetable oil (partially hydrogenated soybean oil, partially hydrogenated cottonseed oil), water, corn syrup, high fructose corn syrup, cornstarch, mono & diglycerides, natural & artificial flavors, salt, guar gum, phosphoric acid, polysorbate 60, potassium sorbate (preservative), sodium benzoate (preservative))