Preheat oven to 350F. Coat a large donut pan* with cooking spray or butter.
Dip or spread frosting on cooled donuts (x2 if you so choose) then garnish with sprinkles and/or striped colored frosting.
In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl with a whisk), beat the cream cheese, butter, and vanilla flavoring together until completely smooth. Add in the powdered sugar, salt, and splash of milk then continue to beat until a smooth frosting forms. If you wish to garnish with frosting stripes, scoop about 1/4 cup of white frosting into a small bowl, add food coloring of choice then mix until correct color forms. Transfer colored frosting to a piping bag with a small opening tip then pipe stripes onto donuts as you see fit :)
*This is the donut pan I used! Total time includes cooling and frosting time.