Use a handheld or stand mixer with the whisk attachment. Cream the vegan butter on medium speed until creamy, approximately 2 minutes. Add the vegan peanut butter and mix until creamy.
Add the powdered sugar, one cup at a time, mixing on low until it's incorporated between each addition.
Add the peanut butter powder and vanilla. Mix until combined.
Add the vegan creamer one tablespoon at a time and mix on medium-high speed until light, fluffy, and spreadable.
Store frosting in an airtight container in the fridge for up to 2 weeks. When you're ready to use it, allow it to come to room temperature and maybe even add another teaspoon or two of plant-based milk until the spreadable consistency returns.
For Vegan Creamer: I recommend using the type of creamer used for coffee, such as Silk Creamer or Ripple Half & Half. You can substitute coconut milk or soy milk.