Frost your cupcakes. LISTEN to me when I say, frost them as you go! You do not want to do them all at once like I did because then the marshmallows have a hard time sticking to the icing.
To Make the Popcorn
Cut the marshmallows in half.
Firmly press them back together so your fingers are basically touching. This creates the popcorn-like dimple.
Stick 'em onto the icing!
Fill the cupcake with as many as you can.
Dilute yellow food coloring with water. You want it to be really light so start with one drop only and work your way up if need be.
Paint the yellow "butter" on the marshmallow popcorn.