4 tablespoons unsalted butter, plus more for greasing the dish and serving
1 3/4 cups all-purpose flour
1 1/2 teaspoons baking powder
1 teaspoon baking soda
6 tablespoons sugar
Kosher salt
1 3/4 cups buttermilk
7 large eggs
2 cups half-and-half
1 teaspoon pure vanilla extract
Maple syrup, for serving
Blueberries, for serving