• Preheat the oven to 325 degrees Fahrenheit. Line a 12-count muffin pan with paper cupcake liners and set it aside.
• Whisk ½ cup vegetable oil, ¾ cup warm coffee, 1 large egg, and 1 ½ teaspoons vanilla extract in a large bowl until combined.
• Sift together 1 ½ cups all-purpose flour, 1 cup granulated sugar, 6 tablespoons unsweetened cocoa powder, 1 teaspoon baking soda, ¼ teaspoon baking powder, and ½ teaspoon salt in a separate bowl. Add the flour mixture to the oil mixture and whisk until fully combined.
• Scoop the batter into the prepared muffin pan, filling the cupcake liners ⅔ of the way full. Bake for 18-22 minutes, or until the centers of the cupcakes spring back when lightly pressed on. Cool completely before frosting.

Chocolate Buttercream

• Add 1 cup softened unsalted butter to a large bowl and beat with a stand mixer fitted with the paddle attachment or a hand mixer until fluffy. Add 3 cups powdered sugar to the butter and mix slowly, increasing the speed gradually until it is fully incoporated.
• Scrape down the sides and the bottom of the bowl and add ½ cup unsweetened cocoa powder, 3 tablespoons milk, 1 teaspoon vanilla extract, and ¼ teaspoon salt. Beat on medium-high speed until completely smooth and combined. If the frosting is too stiff, add more milk one tablespoon at a time until it is a pipeable consistency.
• Use a large star tip to pipe the frosting onto the tops of the cooled cupcakes and serve.