Heat the oven to 375°F. Grease an 8-inch square baking dish.

Mix the oats, baking powder, cinnamon, and salt in a bowl.

Whisk the eggs, milk, maple syrup, butter, and vanilla in another bowl.

Pour the wet mixture into the oats and stir in the blueberries.

Spread the mixture in the dish and bake for 35 minutes, until set.

Cool, cut into squares, and freeze in a sealed container. Reheat one square for 60 to 90 seconds.