Start mixing butter on medium/low, turn down to lowest setting
Add 2 lb powdered sugar to separate bowl and remove 1/2 cup of the powdered sugar
Add 1/2 cup cocoa powder to powdered sugar
Add half of the powdered sugar mixture to butter on low
Add the vanilla bean paste or extract and 2 tbsp of the light corn syrup
Add remaining powdered sugar mixture
Add the 2 remaining tbsp of corn syrup and salt to taste
Mix on med-low to medium until rolled buttercream forms!