In a large bowl using an electric mixer, cream butter and peanut butter until creamy and smooth. Add vanilla extract and salt; mix until combined.
Slowly add powdered sugar 1 cup at a time; beating well after each addition. Scrape down bowl as necessary.
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 Peanut Butter Buttercream in airtight container in refrigerator for 1 week. When you are ready to use, bring to room temperature and re-whip.