Grease a large microwave-safe mug and set aside.
In a separate bowl, combine almond flour, cocoa powder, and baking powder.
Add maple syrup, vanilla extract, melted butter, and egg to the dry ingredients and mix until smooth. If the batter is too thick, add a splash of milk.
Fold in the chocolate chips.
Transfer the batter to the greased mug. Microwave on high until thoroughly cooked, about 60-90 seconds (cooking time will vary depending on the microwave). Allow the mug cake to rest for 1 minute before serving.