Start by preheating your oven to 350°F (175°C). Line a muffin pan with 12 cupcake liners and set it aside for later.

In a large mixing bowl, pour in 3/4 cup of warm water and stir in 1 1/2 teaspoons of instant espresso or coffee powder until fully dissolved. Add 1/3 cup of melted chocolate chips and 1/3 cup of sifted unsweetened cocoa powder. Whisk everything together until smooth and well combined.

Next, whisk in 2 large eggs, 1/3 cup of vegetable or canola oil, 1 teaspoon of vanilla extract (or vanilla bean paste), and 1 teaspoon of white vinegar. Once the wet ingredients are fully incorporated, 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 the batter just until everything comes together—it should be thin, which is exactly what you want.

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

While the cupcakes are baking and cooling, prepare the peanut butter buttercream. In a large bowl or the bowl of a stand mixer, beat 1 cup (2 sticks) of unsalted butter at room temperature with 1/2 cup of creamy peanut butter. Mix on medium speed for about 30 seconds using a hand mixer or stand mixer with the paddle attachment, until the mixture is smooth.

Add 1 teaspoon of vanilla extract (or vanilla bean paste) and 1/4 teaspoon of fine salt, and mix on low speed. Gradually add 4 cups of powdered sugar along with 1/4 cup of heavy cream, continuing to mix on low until fully incorporated. If the frosting is too thick, add another tablespoon of cream; if too thin, mix in an extra 1/4 cup of powdered sugar. Finish by stirring the frosting by hand with a rubber spatula for a few minutes to make it ultra-smooth. Transfer the buttercream to a large piping bag fitted with a round tip and secure the top with a clip or rubber band. Set aside.

To make the ganache, place 1/2 cup of semi-sweet chocolate chips into a heatproof bowl. In a separate microwave-safe bowl, heat 1/3 cup of heavy cream for 45 seconds to 1 minute, just until it begins to bubble and steam. Alternatively, heat it on the stovetop until it reaches a simmer.

Pour the hot cream over the chocolate chips, ensuring they’re completely submerged. Let it sit undisturbed for 1–2 minutes. Then stir gently until the mixture becomes silky and smooth. Set it aside to cool for about 10 minutes, or until it's slightly warm to the touch.

Once your cupcakes are fully cooled, use the wide end of a large piping tip or a small knife to cut out the centers of each cupcake. Spoon in just under 1 tablespoon of your favorite peanut butter into each cavity.

Pipe a generous swirl of the prepared peanut butter frosting on top of each cupcake. Place the frosted cupcakes in the refrigerator for 15 minutes (or the freezer for 5 minutes) to help the frosting set.

While the cupcakes chill, microwave the remaining peanut butter for about 10 seconds, or until it's runny enough to drizzle. Remove the cupcakes from the fridge or freezer and finish them off by drizzling the top with both the chocolate ganache and warm peanut butter. For an added touch of flavor and texture, sprinkle chopped peanuts or a pinch of flaky sea salt on top.