Here is the recipe and guide on how to make make strawberry milkshake buttercream.
This recipe will allow you to fill a 7 inch round cake, or around 6-8 cupcakes depending on how much of the buttercream you use. You may wish to double up the recipe if you are trying to cover and fill the cake with the strawberry buttercream.
Tip:- Remove the butter from the fridge 30 minutes before making this buttercream in order for the butter to soften.
100 grams / 3.5 oz Unsalted Butter (Softened)
165 grams / 6 oz Icing Sugar (Confectioners Sugar USA)
50 grams / 1.7 oz Nesquik Strawberry Milkshake Powder
½ Tablespoon Milk
Then add an additional ½ Teaspoon of Milk to the mix.