This Mint Oreo Cake makes for one fabulous birthday cake for mint chocolate lovers! Dark chocolate cake and tons of whole Oreos are covered in fluffy mint cookies and cream buttercream, then garnished with chocolate ganache and even more cookies.
Preheat oven to 350 degrees F. Grease 3 6-inch cake pans and line with a round of parchment. Grease the parchment then set aside.
In a bowl, whisk together dry ingredients and set aside.
In a separate bowl, cream butter and sugar with a mixer for 2-3 minutes until combined. Add eggs, vanilla, and buttermilk and mix until well combined. Sift dry ingredients into wet and beat until just combined. Mix in the hot coffee in on low speed, beating well.
Divide batter evenly between pans, then bake for 30-35 minutes until a toothpick inserted in the center comes out clean.
Cool in pans for 5 minutes, then transfer to a rack to cool completely. Chill in the refrigerator until ready to assemble.
Mint Oreo Buttercream
Separate 12 of the Oreo cookie from the cream; place the cream in a bowl. Place the cookies in a zipper bag or food processor and crush them coarsely. Set aside.
In a mixer, cream butter on medium-high speed 4-5 minutes until fluffy. Add the reserved Oreo cream, about two cups of powdered sugar, and a pinch of salt. Mix on low until incorporated, then increase speed to medium. Taste and add additional powdered sugar as desired.
Add cream, extracts, and food coloring and mix on low speed until incorporated. Increase speed to medium-high and whip 5-6 minutes until fluffy. Fold 3/4 of the crushed Oreo cookies into icing.
To assemble, place one layer of cake on a cake board or serving plate. Spread a thin layer of buttercream on top, place 7 Oreos on top, then spread another thin layer of buttercream on those. Repeat with the following layer. of cake Set the third cake layer on top, then cover the entire cake in remaining buttercream.
Cover the top of the cake in warm chocolate ganache, then allow it to drip down the sides, helping it along with a spoon or offset spatula.
Pipe stiff ganache rosettes all around the outer edge of the top of the cake, with one in the middle. Arrange remaining 6 Oreos on top of the cake. Use remaining Oreo crumbs to garnish the base of the cake.