Preheat oven to 350. Place butter in a 11" x 8" or 9" pie pan and slide into the oven to melt while the oven is pre-heating.
While the oven is preheating, whisk the dry ingredients together. In a small bowl, whisk the eggs. Make a well in the center of the dry ingredient mixture and add the eggs, milk and vanilla. Stir together until blended.
Remove the pan from the oven and sprinkle berries on top, then pour in the batter.
Bake for 20 minutes.
Take the pan out of the oven and turn it over onto a cutting board for easy slicing, or slice right from the pan. (It will get nice and poofy while it's baking but will sink considerably after turning it out of the pan). Serve with extra berries, syrup or powdered sugar.