Start by preheating your oven to 350°F (175°C). Line a standard 12-cup muffin pan with cupcake liners and set it aside. In a large mixing bowl, pour in 3/4 cup of warm water. Add 1 1/2 teaspoons of instant espresso or coffee powder and stir until it’s completely dissolved. Stir in 1/3 cup of melted chocolate chips and 1/3 cup of unsweetened cocoa powder, whisking until smooth and fully blended.

Next, add 2 large room-temperature eggs, 1/3 cup of vegetable oil, 1 teaspoon of vanilla extract, and 1 teaspoon of white vinegar. Whisk these into the chocolate mixture until well combined. Then, add 3/4 cup of all-purpose flour, 3/4 cup of granulated sugar, 1/2 teaspoon of baking soda, and 1/2 teaspoon of fine salt. Gently whisk everything together until the batter is just combined—it will be thin, which is exactly how it should be.

Divide the batter evenly among the cupcake liners, filling each about 3/4 of the way full. Bake for 18–20 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs. Once baked, remove the cupcakes from the oven and let them cool in the pan for 10 minutes. Then transfer them to a wire rack to cool completely. If you're short on time, you can place the entire pan in the freezer for 30 minutes to speed up the cooling process.

While the cupcakes are baking and cooling, make the peanut butter buttercream. In the bowl of a stand mixer or a large mixing bowl, beat 1 cup of room-temperature unsalted butter with 1/2 cup of creamy peanut butter for about 30 seconds on medium speed, using either a paddle attachment or a hand mixer, until smooth and creamy. Add in 1 teaspoon of vanilla extract and 1/4 teaspoon of fine salt, mixing on low speed.

Gradually add 4 cups of powdered sugar along with 1/4 cup of heavy cream, continuing to mix on low speed. Beat until all ingredients are fully combined and the frosting reaches a smooth, pipeable consistency. If the buttercream feels too thick, add an extra tablespoon of cream. If it seems too thin, mix in another 1/4 cup of powdered sugar. Once the desired texture is achieved, stir the frosting by hand with a rubber spatula for a few minutes to make it ultra-smooth. Transfer the frosting to a large piping bag fitted with a wide round piping tip. Twist and seal the top of the bag with a clip or rubber band, then set it aside.

Place 1/2 cup of semi-sweet chocolate chips in a heat-safe bowl and set it aside. In a separate microwave-safe bowl, heat 1/3 cup of heavy cream for about 45 seconds to 1 minute, or until it starts to steam and just begins to bubble. Alternatively, you can heat the cream on the stove over medium heat until it reaches a gentle simmer, then remove it from the heat.

Pour the hot cream over the chocolate chips, making sure they’re completely submerged. Let the mixture sit undisturbed for 1–2 minutes. Then stir slowly until the ganache is smooth and glossy. Allow it to cool for about 10 minutes, until it reaches a lukewarm temperature—ideal for drizzling.

Once the cupcakes are fully cooled, use a cupcake corer, large frosting tip, or small knife to remove the center from each one. Spoon just under a tablespoon of creamy peanut butter into the hollowed center of each cupcake.

Pipe a generous swirl of peanut butter buttercream onto each cupcake. Place the frosted cupcakes in the fridge for 15 minutes, or in the freezer for about 5 minutes, to let the frosting firm up slightly. Meanwhile, microwave the remaining peanut butter for around 10 seconds until it becomes smooth and pourable.

Remove the cupcakes from the fridge or freezer, and drizzle each one with the slightly cooled chocolate ganache and warm peanut butter. Finish with a sprinkle of chopped peanuts or a pinch of flaky sea salt for an extra touch of texture and flavor. Enjoy!