In a bowl of a stand mixer fitted with a whisk attachment add the room temperature butter. Beat the butter at high speed for 5 to 10 minutes. Scrape down the sides of the bowl often and beat again. As you do this you will notice the color of the butter changing and becoming whiter. The butter is ready when all of it is fluffy and light in color.
Change the attachment of the stand mixer to a paddle attachment and add the powdered sugar. Beat at low speed until incorporated.
Add the cubed and softened cream cheese to the butter and powdered sugar mixture and beat again at medium speed. Make sure you are scraping down the sides of the bowl often to ensure that the frosting is beating evenly.
Add the vanilla extract and peanut butter and beat again at medium-high speed for about 3 minutes until light and fluffy. Scrape down the sides and bottom of the bowl often with a rubber spatula.
The frosting is now ready to use on cakes and cupcakes, enjoy!