This is the easiest icing you will ever make. If you want it more marshmallowy, closer to marshmallow fluff, you can use the entire bag of marshmallows. If you are using it as a cream-cheese icing replacement, up the lemon juice. Its perfect with carrot cake!
1/2 bag of regular marshmallows (use vegan if you wish)
2 tbs vegan butter
2 tbs non-dairy milk as needed (I use coconut cream)
2 cups icing sugar (you may need more to get the consistency you like)
1 tsp vanilla
1 tsp lemon juice
1 pinch of salt (optional)
Using a large, microwave safe bowl, melt the marshmallows and butter (about 1-1.5 mins). Marshmallows get huge in the microwave, so make sure you have enough room. You can also just melt them in a pot on the stove.
Once your marshmallows are softened, add the non-dairy milk (I like to use very cold coconut whipping cream) and vanilla and begin whipping at high speed with hand-held mixer. When the mixture is glossy and well combined, begin adding your powdered sugar, a little at a time. Continue whipping as you add the sugar. When you reach the consistency you need, add your lemon juice and salt, if using. You could also add things like strawberry powder to flavour/colour the icing. Whip again at high speed, tasting as you go.
I like to chill this icing in the fridge, then give it another quick whip before piping/spreading. This is a great icing for making ahead of time.