Preheat your oven to 350℉. Place 2 tablespoons of unsalted butter into a 9x13 casserole dish. Set the dish in the oven as it preheats to melt the butter, which should only take a few minutes. Once melted, carefully remove the dish and brush the butter over the bottom and sides to prevent sticking.

In a large bowl, whisk together 2 cups of all-purpose flour, 4 teaspoons of baking powder, 1/4 teaspoon of baking soda, 1/4 teaspoon of salt, and 2 tablespoons of granulated sugar. This ensures that your leavening agents and seasonings are well-distributed.

Melt 1/4 cup of unsalted butter in the microwave and allow it to cool slightly. Make a well in the center of your dry mixture and add the melted butter, 2 cups milk, 1 egg (at room temperature), and 2 teaspoons vanilla. Using a whisk, mix everything together until no lumps remain in the batter. I like to ensure everything is at room temperature for a smoother, lighter batter.

While your batter rests for a moment, lightly toss 2 cups of fresh blueberries with 1 teaspoon of all-purpose flour. Make sure every berry is coated; this helps prevent the berries from sinking to the bottom during baking.

Pour the prepared pancake batter into the buttered casserole dish (from Step 1). Evenly sprinkle the flour-coated blueberries (from Step 4) over the top of the batter, distributing them as evenly as possible.

Place the assembled casserole into the preheated oven and bake for about 30 minutes, or until the pancake is golden and set in the center. Baking time can vary by oven, so check for doneness with a toothpick inserted in the center—it should come out clean.

Remove the casserole from the oven. Optionally, sprinkle the top with 1 tablespoon of powdered sugar for a sweet finish. Cut into squares and serve warm, perhaps with your favorite syrup. I find a dusting of powdered sugar adds a nice touch—even kids love it!