Preheat the oven to 350 degrees. Line your baking sheet(s) with parchment and set aside.

In the bowl of a stand mixer, combine the sugar and softened butter. Cream until smooth.

Add in the egg and vanilla and mix until combined.

Add in one cup of flour. Mix on low speed until combined.

Add in another cup of flour and mix until combined.

Turn out the cookie dough onto the counter. Knead in the remaining cup of flour until cohesive.

Roll out the cookie dough approximately ⅜ of an inch thick. Using a bunny cookie cutter, cut out the shapes and carefully transfer to the prepared pan(s). Reroll and cut the scraps as many times as you can.

Bake the cookies in the preheated oven for approximately 10-12 minutes or just until the edges are set and the center is no longer glossy. Do not wait for them to turn golden brown or they will be crunchy.

Allow to cool completely before decorating.

In the bowl of a stand mixer, combine the softened butter, vanilla, salt and about one cup of the powdered sugar. Mix on low speed until combined.

Add in another cup of powdered sugar and a dash of milk or water. Mix until combined.

Add in the remaining powdered sugar and mix on low speed until combined. Bump up the speed to medium and mix for an additional minute or so, until the frosting is light and fluffy looking.

Scoop out about ½ of a cup and transfer to a piping bag fitted with a small star tip.

Divide the remaining frosting between three bowls. Tint one yellow, another pink and the last one purple. Transfer the tinted frosting to their individual piping bags (no tip needed).

Once the cookies are cool, cut a small hole off the tip of a tinted frosting bag. Pipe the cookie with an even layer of frosting. Use a knife or spatula to even out the frosting if needed. Sprinkle with the same color of sanding sugar or place the sprinkles on a plate and then invert the cookie and press the frosting into the sprinkles. Either way works.

Repeat with each of the colors.

Pipe a small tail on each of the cookies with the white frosting fitted with the star tip.

The buttercream will crust if allowed to set uncovered.