Bake the cupcakes as per your package directions, but fill them up more than normal (about 3/4 full). This will give you a larger top since the flat edge bottom acts as the body. Cook until baked through and set aside to cool completely.
Make your green frosting by adding 3 drops of green food coloring and 1 drop of yellow food coloring to the frosting can. Stir well to combine. Add more of either color as desired until you get your desired shade of green.
Frost your cupcakes: Frost all cupcakes in your Yoda green frosting. Smooth the frosting out completely by running the knife or spatula under water and then smoothing out the frosting. You can also mound up the frosting in the middle to give them more of a rounded head if desired.
Twist the halves of the sandwich cookies apart, trying to keep the filling on one side.Did the filling split? No problem, you can scrape it and easily press it back where you want it.Take the cookie with the filling on it and cut it in half with a sharp knife.
Make the Ears: Put some pink sugar sprinkles in a shallow plate or bowl. Press the cookie filling side into the sugar sprinkles until covered in pink.Get your green frosting. You want to cover the edges of the ears where you see the cookie in the frosting. I did not frost the back of the ears because they became too heavy and would fall off when assembled.For me, the easiest way to do this was to hold the ear at a corner (the corner you are going to press into the head - perfect for cookies that might break at the corners).Get a knife or skinny spatula and really load it up with a ton of the frosting. Then rotate the edge of the ear through the frosting mound on both the curved and flat edge.Gently take the ear and press the non-frosted corner into the head until it stays put, at the angle you want the ears at. This is typically right above where the flat cupcake edge meets the rounded head.Really press them in there so they stay put! Repeat with second ear.
Take two brown MnMs and place them as eyes, "m" side down, on the head. I found that angling the eyes so they stick up off the cupcake a little made it look better than laying the eyes completely flat (see pictures).
Want to give him a robe? Cut up some brown parchment or butcher paper into strips the height of the cupcakes' flat edges, wrap around, and secure with a little twine or string.
Notes
You might need a second can of frosting depending on how thick you put it on the cupcakes and ears.