Set your oven to 160ºC/320ºF (for standard ovens) and place cupcake liners into a 12-cup muffin tray. It’s almost time to start baking these delicious treats!
Boil 120g of water, then set it aside to cool just a bit. We’ll add this to the batter to give the cupcakes a smooth and rich texture.
Mix the sugar, cocoa powder, flour, espresso powder, baking powder, baking soda, and salt in a large bowl using a whisk. This mixture will form the base of your perfectly chocolatey cupcakes.
Next, blend the sour cream, vegetable oil, eggs, and vanilla extract in a separate bowl. Stir in the cooled water and whisk everything together gently. Ensuring the ingredients are just combined, without overdoing it.
Add the wet ingredients to the dry ingredients in small increments, stirring softly to achieve a smooth batter. Take your time and enjoy the process.
Distribute the batter evenly into the cupcake liners, making sure each is filled two-thirds of the way for the ideal rise. Don’t stress about perfection, the cupcakes will rise beautifully on their own.
Put the muffins in the oven for 20 to 23 minutes, keeping an eye on the rise of the tops. Once done, insert a toothpick to confirm they’re ready.
Let the cupcakes sit in the tray for 5 minutes once out of the oven, then remove and set them aside to cool fully.
While the cupcakes cool, make the Oreo buttercream. Grind 6 Oreos into a fine crumb using either a food processor or the classic rolling pin method.
Beat 200g of butter on medium-high-speed using a stand or hand mixer for 3 minutes, until it becomes soft and creamy. After scraping the bowl, mix for another 3 minutes to achieve a perfectly aerated butter.
Add 300g powdered sugar, 1 teaspoon vanilla extract, and 2 teaspoons milk in two parts, mixing on low speed between each addition. Once everything is mixed, scrape the sides of the bowl and continue blending until the mixture is smooth and creamy.
Blend the crushed Oreo crumbs into the buttercream, mixing just enough to combine. This will give your frosting that delicious cookies-and-cream taste.
Fill a piping bag with the Oreo buttercream, using a round tip (like Wilton 1A), and pipe onto each cupcake after they’ve cooled. Add a whole Oreo on top and indulge!