Prepare brownies according to directions and allow to fully cool before frosting.
Mint Frosting
Use a handheld mixer or stand mixer to whip shortening for 5 minutes on high until light and fluffy. Gradually add mint extract to taste, mixing and scraping down the sides of the bowl.
Add in spinach puree 1 tsp at a time to achieve desired color*
Notes
*The frosting color will depend upon how many teaspoons of spinach puree added. There is a spinach flavor, although mild, it is there. Add less spinach to help mask the flavor
Recipe by Petite Allergy Treats at https://petiteallergytreats.com/mint-chocolate-brownies-gluten-free-vegan/