Add Oreos to a food processor and blitz until even crumbs form. If you don't have a food processor, then add the cookies to a zip lock bag and crush them using a rolling pin or any other blunt object.
Next, whisk unsalted butter in a bowl for a few minutes.
Add ⅓ of the icing sugar to the butter bowl and mix with a spatula for a minute to prevent the sugar from spilling while whisking. Then, whisk the ingredients until combined. Repeat this with the remaining sugar, add 1 teaspoon of cocoa powder, ¼ teaspoon of vanilla extract and whisk until fluffy.
Then, add the Oreo crumbs to the buttercream and mix with a whisk or spatula until combined.
Add the Oreo buttercream to a pipe and nozzle and frost your favorite desserts!
Notes
Unsalted butter: Make sure the butter is at room temperature before mixing. This will give the buttercream a smooth consistency.
Frosting: Use an angled cake spatula or pipe and nozzle to frost the desserts.