This recipe makes enough frosting to fill and frost an 8-inch round with 3 layers. I made a 6-inch cake and opted to frost only the top, I freeze my left over frosting for another use. You could make half the recipe but will still likely have a bit left over if you only frost the top.
*Once browned the butter will reduce to about 200g, if you're substituting vegan butter/margarine, use 200g and not 250g
**I never used to like these types of frosting till I discovered the grittiness you sometimes get is due to cornstarch. I now use an organic brand that uses tapioca starch and the finish is much smoother