This depends on your personal preference,sugar is optional,milk can be used,and,plant-based butter can also be utilized.Both have their pros and cons.Eggs are essential,mousse is a common option,though they each have their own advantages and disadvantages.Milk cream is healthier but has slightly less whipping stability, while plant-based butter may affect health but is easier to whip.Therefore, you can mix the two for whipping, which balances both healthiness and ease of whipping.However, this isn't necessary; most store-bought birthday cakes use only plant-based butter.