Blueberry Pecan Overnight Baked Oatmeal

In a medium mixing bowl, combine the 2 cups of old-fashioned rolled oats, 1/2 cup light brown sugar, 1 teaspoon baking powder, 1 1/2 teaspoons cinnamon, and 1/2 teaspoon salt. Whisk briefly to distribute the spices evenly.

In a separate large bowl or large liquid measuring cup, whisk together the 2 cups of whole milk, 2 large eggs, 3 tablespoons of melted butter, and 1 teaspoon of vanilla extract until the mixture is homogenous.

Grease a 2-quart baking dish (approximately 8x8 inch or 9x9 inch) with a small amount of butter. Scatter 1 cup of the blueberries across the bottom of the dish.

Pour the dry oat mixture over the blueberries in an even layer. Then, slowly pour the wet milk mixture over the oats. Gently shimmy the pan to ensure the milk settles into the oats. Top with the remaining 1/2 cup of blueberries and the 1/2 cup of chopped pecans.

Cover the dish tightly with plastic wrap or a lid and refrigerate for at least 8 hours, or overnight. This resting period is crucial for the oats to absorb the liquid and develop the correct texture.

When ready to bake, preheat the oven to 375°F (190°C). Remove the oatmeal from the refrigerator and uncover it while the oven heats up to take the chill off.

Bake for 35 to 40 minutes, or until the top is golden brown and the center is set (it should feel firm to the touch, not liquid). Let cool for 5 to 10 minutes before slicing into 6 squares.