Preheat oven to 350 degrees
Follow the directions on the back of the brownie box in order to bake the brownies
Tear off a large sheet of parchment paper so that the sides come up over the 9x13 baking dish
Pour brownie batter into the baking dish and bake in the preheated oven for 25-30 minutes or until a toothpick comes out clean
Let brownies completely cool
Using a standing mixer, mix together the egg whites, cream of tartar, vanilla, and powdered sugar and mix until stiff peaks form
Once the royal icing is made, spit into 2 bowls
Add a few drops of brown into 1 bowl and mix. Add in a few more drops to get the shade you want
Repeat step with the pink coloring in the second bowl
Scoop a little bit of icing into the piping bags
Add 2 teaspoons of water into the brown royal icing and mix until combined
Pour into the squeeze bottle
Carefully lift the parchment paper out of the baking dish with the brownies and place onto the counter
Using the cookie cutter, cut out 6 bunnies
Place cut out bunnies onto a cookie sheet
Using the piping bag with the brown icing, outline the shape of the bunnies head.
Fill in with the brown thinned icing
Add 2 large eyes into the center of the bunny
Let icing dry for 2 hours before adding the final details
Once the base layer is dry, using the pink piping bag, pipe a upside down triangle under the eyes
Pipe the pink for the ears
Using the brown icing, pipe cheeks on the bunny
Let the cheeks dry for an hour before adding on the small dots for the "whiskers"
Let bunny completely dry for an hour before enjoying!