This delicious vegan buttercream is fluffy, creamy, easy to use, and pipes beautifully!
If you are using vegan butter sticks, let them warm up to room temperature on the counter and do not try to soften them in the microwave. If you are using tub spread, skip this step and use it cold from the fridge.
Add the shortening to a large mixing bowl and beat on medium speed until it is smooth and fluffy. Any lumps left in now are likely to still be in the finished frosting.
Add the softened stick spread or cold tub spread, and beat again until light, fluffy, and free of any lumps.
Scrape down the bowl again, then add the salt and 1/3 of the powdered sugar. Beat to mix in the powdered sugar.
Add half of the remaining powdered sugar and 1/3 of the light coconut milk. You can use another plant milk, but light or regular coconut milk gives the buttercream a very nice and creamy texture without adding any color. Mix again.
Scrape the sides and the bottom of the bowl really well to remove any hint of fat from the bowl. This step prevents streaks in your frosting later. Either switch to a clean spatula or wash and dry the used one.
Add the rest of the powdered sugar and half of the remaining milk. Beat again. Check the consistency of your buttercream. If it is the spreading consistency that you want, do not add any more milk. If it is too thick (as it most likely will be), add a little more milk to get it the way you want it to be. I almost always use the full amount of milk and sometimes need a bit more. Only add 1/2 tsp more at a time when it is getting close. Also, remember that you will be adding a little more liquid later if you are tinting your frosting. Beat again, then scrape the bowl.
Next, whip the buttercream on high speed for two to three minutes until it has lightened and become very light and fluffy. Scrape down the bowl again. Your buttercream is done and you can use it immediately. (This is when you will add food coloring if you are tinting your frosting.)