Combine all ingredients in a mug. Stir until well mixed.
Microwave at high power for 1.5 - 2.5 minutes or until the top is springy to touch.
Serve warm.
Notes
As mug sizes vary and microwave ovens often differ in wattage, the cooking time may vary. Please experiment, starting with the shortest amount of cooking time and increasing by 20-30s increments until the cake is just cooked.
Recipe by Provincial Paleo at http://www.provincialpaleo.com/grain-free-banana-mug-bread-aip-friendly/