In a large bowl using an electric mixer, cream butter and shortening until creamy and smooth. Add vanilla and butter extracts; mix until combined.
Turn mixer on lowest speed and slowly add 1 lb of powdered sugar; mix until creamy. Scrape down bowl as necessary. Adding the powdered sugar gets dusty - place a damp towel over the top of the mixer to shield flying powdered sugar dust.
Continue to slowly add remaining powdered sugar; blend until completely combined.
Once all powdered sugar has been mixed in, add 1 tablespoon of milk at a time and mix. Continue to add and mix until desired consistency is achieved. Eat & Enjoy!
Notes
Store Vanilla Buttercream in an airtight container in the fridge; will keep 2+ weeks.
When you are ready to use, thaw to room temperature and re-whip; adding milk as needed.¹ For a creamy buttercream use pure cane sugar powdered sugar. If it doesn't say "pure cane sugar" it is beet sugar, which can leave buttercream gritty.² Pure non-clear vanilla extract can be used instead of clear vanilla extract, however this will effect the color of the buttercream. It will make it less white.³ Butter vanilla adds more butter flavor to the buttercream; it is subtle and worth adding but is not necessary.Recipe from Rose Bakes.