For the Cupcakes:

1. Preheat the oven to 350 degrees. Line a 12-cup muffin pan with cupcake liners. Set aside.
2. In a large bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt until thoroughly combined. Set aside.
3. In another bowl, whisk together the eggs, both the white and brown sugars, the oil, and the vanilla.
4. Pour half of the egg and sugar mixture into the dry ingredients. Then add half of the buttermilk. Gently whisk and then repeat with the remaining wet ingredients and buttermilk. Stir until just combined being careful not to overmix.
5. Spoon the batter into the liners filling them only 1/2 way. This batter rises so you want to be careful not to overfill! If you have extra batter, don’t top. It’s better to make additional cupcakes.
6. Bake for 18-20 minutes, rotating the pan halfway to ensure even baking. If you’re not sure if the cupcakes are done, you can stick a toothpick into the center of the cupcake. If it comes out clean, they’re ready.
7. Allow the cupcakes to cool completely before frosting. 

For the Frosting:

1. Using a handheld or stand mixer fitted with a paddle attachment beat the butter and the cookie butter on medium speed until creamy, about 2 minutes.
2. Add the confectioners’ sugar, salt, and 1 tablespoon of the cream (or milk or half-and-half). Beat on low speed until some of the sugar is incorporated, about 30 seconds. Then increase to medium-high speed and beat for 2 minutes.
3. Adjust if necessary. If the frosting is too thick, add more cream (one tablespoon at a time) until you get the desired texture. You can also add more sugar if it’s too thin.
4. Use frosting immediately or cover tightly and store for up to 5 days in the refrigerator.