Single-serve low-carb mug cake made grain-free and sugar-free with 5 ingredients.
Add all ingredients to a microwave safe mug and stir until well-combined. Note: make sure your butter has cooled before adding it, or else it will melt the chocolate chips before microwaving.
Microwave on high for 45 to 60 seconds, until cake has risen and has a few air bubbles. Note: for a cookie-like consistency, microwave for 30 to 40 seconds.