In a bowl, whisk together flour, baking powder, cinnamon, and salt.
Separately, combine pumpkin, maple syrup, almond butter, milk, and vanilla.
Gently fold dry ingredients into wet mixture, until integrated. (Then fold in any desired mix-ins, if using.)
Spray inside of mug (14-16oz) with cooking spray. Add batter.
Microwave 2 minutes 45 seconds, or more/less depending on your microwave wattage. (I tested this recipe in a 900-watt microwave—see cook time guidance below to adjust for your microwave.) Test to see if a toothpick comes out clean.
Allow to cool 1 minute in mug. Place a plate on top of mug, then flip and tap mug with a spoon to remove mug cake. Rest 3-5 minutes before cutting and eating.
When cooking, microwave at least 15-20 seconds less as you test to find the right cook time.
Mug Cake Cook Time & Microwave Wattage
Check your microwave wattage and reference the times listed below—but these times are NOT exact! Start with at least 30 secondsless than the time listed, then continue to cook in short intervals, testing with a toothpick as you go. You will need to experiment to find the right cook time in your microwave.
700-watts: 3 minutes 30 seconds
800-watts: 3 minutes 5 seconds
900-watts: 2 minutes 45 seconds
1000-watts: 2 minutes 30 seconds
1100-watts: 2 minutes 15 seconds
1200-watts: 2 minutes 5 seconds
1300-watts: 1 minute 55 seconds
*If you make this recipe with an egg, it will need to cook for at least 15-20 seconds less.