In a mug stir together oat flour, baking powder, lemon zest, lemon juice, agave syrup, and a pinch of salt.
Bake in the microwave on 1000W for about 1 ½ minute.
Allow to cool for a couple of minutes before serving.
Notes
Don´t substitute oat flour. Oat flour is the base of the cake. Substituting can result in a dry cake. To make this cake gluten-free make sure to use non-contaminated oat flour.
Taste and adjust with additional maple syrup or lemon zest if needed.
Let the cake cool down but eat as soon as possible.
Top with dairy-free whipped cream, vanilla ice cream, or other toppings of your choice.