Add butter to a stand mixer bowl and beat it until it is very smooth.Add remaining ingredients and mix until smooth and well incorporated.Sprinkle a small amount of powdered sugar on your countertop and roll sections of the butter mint "dough" into rolls about the thickness of a string cheese. I like to cover my unused dough with a damp paper towel or a piece of plastic wrap so it doesn't dry. Slice butter mints in small pieces and allow them to set and dry overnight. Store mints in a ziplock bag in the fridge or in an airtight container. I love eating them chilled!