Preheat oven to 325 degrees. Grease and dust with flour two 8 inch round cake pans. I only used half a recipe and two 6 inch cake pans.
In a mixing bowl, add the butter and granulated sugar. Mix until light and fluffy about 3 minutes.
Add in the vanilla bean paste and each egg separately and mix until incorporated.
In a separate bowl, add in the flour, baking powder, baking soda and salt. Stir to combine.
Alternately add the flour and buttermilk always starting and ending with the flour. I did 3 parts flour and 2 parts buttermilk. Scrape down the sides and mix to combine.
Pour the batter into the prepared cake pans.
Place in the oven and bake for 1 hour or until done. Place a skewer into the center of the pan, if it comes out clean or with moist crumbs it's done. If it still has batter, let it bake a while longer and test again.
Let it cool for 10 minutes and then turn out onto a wire rack to cool completely.
In a mixing bowl, add in the butter and mix until creamy.
Add in the peppermint extract, powdered sugar and milk. Mix on low until just incorporated.
Add in the drop or two of gel paste color and mix for another minute or two until light and fluffy.
Add 6 cookies into a food processor or storage bag. Pulse until the cookies form a crumb. If you're using a storage bag, crush the cookies using a rolling pin.
If the cake has a dome, cut it so it's even. Place it on a cake stand.
Add a thin layer of frosting on top of the cake.
Place the frosting in a piping bag with a straight tube. Add a ring of frosting around the edge of the cake.
Fill the center of the cake with all the Oreo crumbs.
Trim the top layer of cake if it's domed. Place it on top of the Oreos.
Add a thin layer of frosting to the outside of the cake. Any frosting that comes out of the center, push it around to fill in any spots.
Place the fridge for about 15 minutes to firm up slightly.
After the crumb coating has set up, cover the cake with a layer of pink frosting.
Add a red strip of gel paste color to the piping bag. Fill it with about ½ cup of pink frosting. Pipe peaks around the cake.
Cut the 4 Oreos in half using even pressure. The even pressure will prevent the Oreos from breaking all apart.