Step 1

Into a 12-ounce microwave-safe mug, add the cocoa powder, flour, sugar, espresso granules (if using), and salt. Stir with a fork. Add the milk, butter, and vanilla, and stir with a fork until smooth. Stir in 3 tablespoons of the chocolate chips. Use a damp paper towel to wipe excess batter off the sides of the mug.

Step 2

Microwave for 2 minutes 45 seconds on high, then sprinkle remaining 1 tablespoon chocolate chips on top. Let the brownie stand for 2 minutes before eating. Serve warm with vanilla ice cream.