1) A stencil. The stencil I used is part of a set called "Flower Explosion." It was designed for cake, not cookies. I do what I want. You can too.
2) Thick royal icing. THICK. Like cookie dough thick. If you think it's thick enough, turn the bowl upside down. If you hesitated -- it's not thick enough.
3) Some sort of flat edge to spread the icing -- spatula, scraper, firm ruler...
4) Cookies. You can stencil on a nekkid cookie, cover it in fondant, or flood it with royal and let it dry overnight before stenciling. I went with fondant because I'm impatient like that.
And then put the icing on just like you did when the stencil was on the counter. As much as I like being normal...I could sure use an extra arm sometimes. I tried to get my 4 year old to take a picture but he just wanted to eat the icing. So imagine a beautiful picture here that answers all your remaining questions. Got it?
And then just stand there and stare at the amazing-ness of your stenciled cookies. Your cookies, not mine. Don't look too close at these little gems. You all make me nervous.