Select a microwave-safe mug that has a capacity of at least 12 ounces to ensure that your muffin has enough space to rise.

In your chosen mug, add ¼ cup of all-purpose flour, 2 tablespoons of white granulated sugar, ¼ teaspoon of baking powder, and a pinch of salt. Mix until evenly combined.

Pour in 3 tablespoons of milk, 1 tablespoon of melted butter or vegetable oil, and ¼ teaspoon of vanilla extract. Stir gently to combine.

Gently fold in 2-3 tablespoons of fresh or frozen blueberries into the batter.

Wipe the edges of the mug with a clean cloth or paper towel to prevent any cooked batter residue from burning.

Place your mug in the microwave and cook on high for 40-60 seconds, starting with 40 seconds.

After microwaving, use a toothpick to check for doneness. If it comes out clean, your muffin is ready.

Carefully remove the mug from the microwave and let it rest for a couple of minutes before enjoying.