This is easy version of those stunning (and sometimes labor intensive) cakes!
In a stand mixer with the paddle attachment, cream shortening and butter on medium-high until fully combined and fluffy, about 3 minutes.
Slowly add sugar, one cup at a time. Add meringue powder. (The mixture will appear dry.)
Add in milk. Turn the mixer up to medium-high (or high) and beat until light and fluffy (approximately 5 to 8 minutes).
buttercream is still too dry, add in more milk 1 tablespoon at a time until you reach the desired consistency. Make sure the mixer is on low speed when adding in milk and give it at least 30 seconds between each addition.
**You can omit meringue power if you prefer. To achieve the perfect piping consistency, you may need to add more confectioner's sugar.
Place directly into piping bags and seal with a rubber band. Can be stored in piping bag until ready to use, up to 3 months.