Preheat the oven to 180°/350°F/Gas 4. Line two cookie sheets with parchment paper and set them aside.

Using an electric handheld or standing mixer, beat the butter, brown sugar, sugar, eggs, and vanilla until combined.

Sieve or whisk the flour, salt, and baking powder in a medium bowl. Stir in the crushed Oreos.

Gradually beat the dry ingredients into the wet ingredients until a soft dough forms.

Using a small ice cream scoop, scoop dough onto the cookie sheets above 3-inches apart.

Bake in the oven for 12-15 minutes or until browned.

Leave the cookies to cool on the cookie sheet for 10 minutes before transferring them to a wire rack to cool completely.

Using an electric handheld or standing mixer, beat the butter, powdered sugar, vanilla, and heavy whipping cream until combined, smooth, and holds a peak.

Scoop 1 cup of frosting into a piping bag fitted with a star tip. Set it aside.

Scoop the remaining frosting into another piping bag. Set it aside.

Place the chocolate chips into a small bowl.

Place heavy whipping cream into a small pot over medium heat and bring to a simmer. Pour over the chocolate chips and whisk for one minute until smooth.

To decorate the cooked and cooled cookies, pipe a thick layer of frosting onto the top of each cookie and smooth it evenly.

Scoop some chocolate ganache onto the center of the frosting and lightly spread it out.

Pipe a swirl of frosting on top of the ganache.

Sprinkle some of the sprinkles on top.

Place the unicorn icing horn and ears into the center of the frosting and enjoy!