First things first, make sure to beat the unsalted butter on medium speed using a stand or handheld mixer fitted with a paddle attachment. With this, ensure to do so for about two minutes or till it is creamy.
3 tbs of milk, or heavy cream, 1 cup of unsalted butter; ensure to soften to room temperature, 3 1/2 cups of confectioner's sugar, 1/2 cup of unsweetened dutch-process or natural cocoa powder
Then, be sure to add milk or heavy cream, confectioner's sugar, and cocoa powder. After that, make sure to beat on low speed for approximately thirty seconds.
Next, be sure to add salt, peanut butter, and vanilla extract. Afterward, ensure to beat on medium-high speed for about two minutes. Remember, make sure to do it till well combined.
1/4 tsp of salt, 1/3 cup of creamy peanut butter, 1 tsp of pure vanilla extract
Afterward, add one-fourth cup more confectioner's sugar. Do this, especially if your frosting is incredibly thin. Likewise, if your frosting is exceptionally thick, you can put another two tablespoons of milk or heavy cream. Also, you may add a spoonful of additional peanut butter. Besides, if desired, you can add a pinch of salt.
Finally, make sure to frost the cupcake, confection, or cake.