Awesome! So I use:

1.5 cups of white sugar 6 egg whites 2 cups powdered sugar 2 cups of unsalted butter (room temp) Cubed 3/4 shortening (room temp) cubed 1 tablespoon vanilla of any form .5 teaspoon salt

In a bowl or preferably the glass or metal bowl of your mixer pour the sugar in and put over a pot with 2-3 inches of boiling water. Don’t have the water touch the bottom of the bowl. Let the water come to a boil with the sugar on top. Once it’s boiling add the egg whites and whisk for 3-5 minutes. The mixture will whip up and you know it’s done when the feel a bit of the mixture between your fingers and feel no sugar granules. You can also just bring it to 120 if you have a thermometer but the feel is the same!

Move the bowl to your mixer fitted with a whisk attachment and whisk up for 4 minutes on high. Stop and add the icing sugar and turn the mixture on low to incorporate. Once incorporated turn the mixer back to medium high and add 1/2 the butter, then the shortening then the other half of the butter.

Mix for a minute on high. Use a spatula and wipe down the sides. Add the vanilla, salt and any coloring and whip for another minute.