Combine the softened butter, white granulated sugar, and brown sugar in a large bowl. Use an electric hand mixer to cream the ingredients together for 1-2 minutes, or until smooth and homogenous.
Add the egg and vanilla. Cream again until the egg is fully incorporated with the creamed butter.
Add the flour, crushed Oreos, baking powder, and baking soda. Fold the dry ingredients into the wet ingredients until no pockets of Oreo or flour remain in the cookie dough. Cover your cookie dough with plastic wrap and chill it in the fridge for 30 minutes.
Preheat the oven to 350°F.
Use a number cookie scoop to drop balls of cookie dough onto a baking sheet. Space them about 2 inches apart. Bake your cookies for 12 minutes. Let the cookies cool on the baking sheet for 5 minutes and then on the counter for another 25-30 minutes.
While your cookies are cooling, prepare your frosting by whisking together the softened butter, cocoa powder, and powdered sugar.
Use a piping bag or spatula to frost your cookies and then top them with a spoonful of crushed Oreo as well as a gummy worm. Enjoy!