Homemade Pumpkin Mug Cake - Choose a microwave-safe mug with a capacity of at least 10 ounces to prevent overflow. Lightly grease the inside of the mug with a bit of oil or cooking spray.
In the mug, whisk together the all-purpose flour, granulated sugar, baking powder, and pumpkin pie spice until well combined. Add the canned pumpkin puree, milk, vegetable oil, and vanilla extract to the mug. Mix everything together until you have a smooth batter.
Place the mug in the microwave and cook on high for about 1 minute and 30 seconds to 2 minutes. Cooking time may vary depending on your microwave's power, so keep an eye on the cake. The cake should rise and firm up. To check if the mug cake is done, insert a toothpick into the center.
If it comes out clean or with a few moist crumbs, the cake is ready. If not, microwave in 15-second intervals until done. Carefully remove the mug from the microwave (it will be hot). Allow the cake to cool for a minute or two before adding optional toppings like whipped cream, chopped nuts, or a sprinkle of cinnamon.
Cake Mix Pumpkin Mug Cake - Prepare large mug with non stick spray. Add 3 tbsp spice cake mix + 1 tbsp pumpkin puree + 1.5 tbsp water until smooth. Microwave for 1 1/2 minutes, allow to cool for a few minutes, then top with Cool Whip!