Melt butter in a microwave-safe mug or ramekin. Then add vanilla extract and the egg. Whisk until yolk is incorporated and mixture is well-combined.
In a small bowl, combine coconut flour, Swerve, and baking powder. Mix thoroughly to combine.
Add dry ingredients to the mug (or ramekin), then mix thoroughly until well-combined.
Place the mug in the microwave for one minute on high.
When finished, put a fork in the mug cake and carefully lift it up and flip it over. If the bottom isn’t fully cooked yet (this will depend on your microwave), cook it for another few seconds.
Your pancake mug cake can be enjoyed in the mug, fully intact on a plate or bowl, or cut in half on a plate or bowl. (I prefer cutting mine in half.) To serve, top with butter, Lakanto maple-flavored syrup, and Swerve Confectioners.
Notes
If you don't have medium eggs on hand, you can use a large egg, but the result might be a bit "eggy."Nutrition facts do not include toppings.