Lightly grease a 12 oz microwave-safe mug (or ramekin or bowl).
Add the dry ingredients and whisk to combine. Then add the wet ingredients and stir until smooth.
Microwave for 1 and ½ to 2 minutes, checking early, until the center is set and bounces back slightly when pressed.*The cake may puff up as it cooks but will sink back down as it cools.
For best texture, allow to sit for 2-3 minutes to set.
Top as desired and enjoy!
Notes
Use Oatmeal In Place of Oat Flour: Replace the oat flour with ⅓ cup + 1 tablespoon rolled oats (40 grams) and then rather than stirring the ingredients together, simply add them all to the blender, blend until smooth and then pour into the cup and microwave..Quick Chocolate Coconut Oil Frosting:While the cake rests for the 2-3 minutes after cooking, melt ½ tablespoon of coconut oil. Then stir in 1 tablespoon of cocoa, ½ tablespoon of maple syrup and a pinch of salt. Drizzle over the mug cake.Cook Time: I give a large range for the cooking time as it varies depending on your model of microwave and the mug size and shape.Leftovers: This is best enjoyed fresh but leftover cake can be stored in the refrigerator for up to 3 days or frozen up to 3 months. When ready to enjoy, simply reheat in the microwave.*Nutrition calculated based on the vanilla base recipe.