Combine chocolate chips and olive oil in a microwave-safe bowl; heat in microwave until melted, about 20 to 30 seconds.
Stir coconut flour, water, and baking soda into chocolate mixture using a fork. Add egg and coffee extract to chocolate mixture; stir well.
Divide batter between 4 microwavable mugs. Heat each mug in microwave until cake is cooked through, about 1½ minutes. Cool cake for about 2 minutes before eating.
Recipe by Keto Diet Cooking -Keto Diet Recipes and More at https://ketodietcooking.com/keto-mug-cake/