Small-Batch Chocolate Cupcakes

Step 1: Preheat the oven to 350°F with a rack positioned in the center. Place four baking cups in a standard muffin pan and lightly grease the baking cups. Space the cups out as you like.

Step 2: To make the cupcakes, sift the sugar, flour, cocoa powder, baking soda, salt, and espresso powder into a small bowl, then whisk briefly to combine.

Step 3: In another small bowl, combine the water, oil, vanilla, and vinegar. Whisk to combine, then pour the wet ingredients into the bowl of dry ingredients and whisk until smooth.

Step 4: Divide the batter evenly among the four baking cups, using 58g of batter per cupcake.

Step 5: Bake the cupcakes for 20 to 22 minutes, until the cake springs back when lightly touched and a toothpick inserted into the center of one cupcake comes out clean or with a few moist crumbs clinging to it.

Step 6: Remove the cupcakes from the oven and let them cool in the pan for 5 minutes before turning them out onto a rack. Let them cool completely before frosting, about 20 to 30 minutes.

Step 7: To make the frosting, combine the milk, vanilla, and salt in a very small bowl or 1/4-cup measure. Stir gently to combine and dissolve the salt.

Step 8: Sift the confectioners' sugar and cocoa powder into a small bowl. Add the butter and stir with a flexible spatula until the mixture is slightly crumbly.

Step 9: Add the milk mixture and continue mixing with a spatula until smooth. Once smooth, whisk vigorously to incorporate air into the frosting; it will become fluffy and lighter in color.

Step 10: Divide the frosting evenly among the four cupcakes, using about 28g per cupcake. A scant 2-tablespoon scoop works well. If desired, garnish the frosted cupcakes with sprinkles.

Step 11: Store leftover cupcakes covered at room temperature for several days.