Step 1: Preheat the Oven

1. Preheat your oven to 375°F (190°C) and line a 12-cup muffin tin with paper liners or grease the cups with nonstick spray.

Step 2: Prepare the Dry Ingredients

1. In a large mixing bowl, whisk together the flour, cocoa powder, baking powder, baking soda, salt, and espresso powder until well combined.

Step 3: Mix the Wet Ingredients

1. In a separate medium-sized bowl, whisk together the granulated sugar, brown sugar, eggs, milk, vegetable oil, and vanilla extract until smooth.

Step 4: Combine Wet and Dry Ingredients

1. Gradually pour the wet ingredients into the bowl of dry ingredients. Gently fold the mixture with a spatula until just combined. Be careful not to overmix, as this can make the muffins dense.
2. Fold in the chocolate chips, reserving a handful for topping.

Step 5: Portion the Batter

1. Divide the batter evenly among the muffin cups, filling each about ¾ full. Top each muffin with a few additional chocolate chips for a bakery-style appearance.

Step 6: Bake the Muffins

1. Bake the muffins in the preheated oven for 18–20 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Avoid overbaking to ensure the muffins stay moist.
2. Remove the muffins from the oven and let them cool in the pan for 5 minutes before transferring to a wire rack to cool completely.

Step 7: Optional Espresso Drizzle

1. While the muffins cool, make the espresso drizzle by whisking together the powdered sugar, espresso powder, and milk until smooth. Adjust the consistency by adding more milk if needed.
2. Drizzle the glaze over the cooled muffins for an extra hit of espresso flavor and a decorative finish.

Step 8: Serve and Enjoy

1. Serve the muffins warm or at room temperature. Pair them with a hot cup of coffee or a glass of milk for the ultimate treat.