Preheat oven to 375°F (190°C). Grease a standard 12-cup muffin tin.

In a large bowl, whisk together 1 cup milk, 1 large egg, and 2 tbsp melted butter until smooth.

Add 2 cups pancake mix and stir until just combined; a few lumps are fine. Gently fold in 1 cup blueberries.

Spoon batter into the prepared muffin cups, dividing evenly and filling each about 3/4 full.

Bake 18 to 22 minutes, until tops are golden and a toothpick inserted in the center comes out clean.

Cool in the pan for 5 minutes, then transfer to a wire rack. Serve warm with butter and maple syrup if you like.