mock creme advice?

Question

can you tell me how to make mock creme to put between a sponge please?

Answer 1

butter and icing sugar mixed

Answer 2

12-oz cartons heavy whipping cream
3/4 cup powdered sugar

Using an electric mixer, whip cream until stiff. Add powdered
sugar 1/4 cup at a time, mixing between each addition. Mix until
stiff and cream forms peaks. Frost cake. Refrigerate before
serving or serve immediately. Cake must be stored in the refrigerator.

Note: The more powdered sugar, the stiffer the icing