I actually found this works a lot better in a high rimmed bowl, but you CAN use a mug if you insist :)
Dry ingredients, mixed in cooking bowl/mug:
2 Tablespoon plain flour
1 Tablespoon quick oats (or plain flour)
1 Tablespoon brown sugar
1/4 teaspoon baking powder
large pinch cinnamon
Wet ingredients, mixed in a different bowl:
1/2 mashed banana
1 Tablespoon chunky peanut butter
dash vanilla essence
Fold the wet ingredients into the dry, don't mix for too long.
Microwave about a 90 seconds on high. Eat right away.
This was nice but a little dry and plain. Not sure if I should increase the banana, peanut butter, or sugar. Or add rice milk? Nice with maple (flavoured) syrup. The spices and vanilla are optional. You can make it without baking powder but it's super dense.
I get cravings for sugar, eggs and carbs sometimes and this fulfills that pretty well hurrah. Adapted from several other recipes, all of which either called for masses of fat and sugar or didn't fit my personal definiton of "cake" (I'm still not sure if I'm brave enough to try this recipe