1. Heat oven to 350 degrees F. Line standard muffin/cupcake tin with paper or foil liners. Place one Oreo cookie bottom with frosting still attached at the bottom of each cupcake liner.
2. Sift together flour, sugar, baking powder, and salt in bowl of standing mixer fitted with paddle attachment. Quickly and on the lowest speed, mix around to make sure everything is evenly distributed.
3. Add softened butter, sour cream, egg and egg yolks, and vanilla extract; on medium speed (start w/ the slowest first or the flour will fly) beat for about 30 seconds or until mixed together. Scrape down sides of bowl with rubber spatula and mix by hand until smooth and no flour pockets remain.
4. Divide the batter evenly in the little paper or tin cupcake liners on top of the Oreo cookie bottom. I used a 3tbsp cookie scoop for a perfect measurement. Place on the middle oven rack and bake for about 20 minutes (check after 18 minutes, no longer than 24) or until lightly golden or toothpick comes out clean.
5. Remove the cupcakes from cupcake pan and cool at room temperature before frosting.

For the Cookies & Cream buttercream:

1. In a large stand mixer (or hand-mixer), whip softened butter for about 3 to 5 minutes, scraping down the bowl as necessary. Reduce the speed to low, and add the powdered sugar and mix until well-incorporated. Increase the speed to medium-high, add the vanilla extract, salt and heavy cream, and whip until frosting is light and fluffy.
2. Toss in your crushed oreos and mix by hand until well incorporated. The amount of cookies for your buttercream is totally up to you. Some may like a lot of cookie bits, some may like less. Do you. Just remember to take into account that you’ve got a whole bottom half of an Oreo at the bottom of the cupcake, and another half at the top.
3. Pipe onto your cooled cupcakes and top each cupcake with a half Oreo.
4. Enjoy 😉