Mash the banana and whisk it together with the egg in a small bowl.
Stir in the protein powder and mix until completely combined (no dry spots).
Portion into a mug or small ramekin and top with any toppings.
Microwave for 2 minutes and let cool a full minute before enjoying.
Video
Notes
The riper the banana, the sweeter the mug cake!Make sure to use a microwave-safe mug. The size of the mug will alter the cooking time so keep an eye on it in the last 30 seconds.It is HOT coming out of the microwave, give it a minute or two to cool down before you dive in and burn your tongue.The protein powder you choose can and will alter the flavor and taste of the 3 ingredient mug cake as some vegan protein powder absorbs differently.I have since switched to use Equip Protein for its amazing taste and third-party testing (use code mamabear to try). If you use this, know you'll need to add 1.5 tablespoons of flour to the mug cake so that it holds together.