Preheat the oven to 400°F or gas mark 6. Grease the sheet pan with baking spray or a tablespoon of melted butter.
Combine the baking soda, flour, baking powder, and salt in a bowl and set aside.
In a mixing bowl whisk the eggs, then add the buttermilk, melted butter, vanilla, and brown sugar. Using a spatula add the flour mixture and mix to combine. Gently fold in the blueberries. Pour onto the lines sheet pan spread evenly.
Bake for 12-15 minutes or until golden brown. The pancake will not be evenly brown or a very dark brown once it is done baking. To get a darker brown turn the oven to broil and brush with melted butter. Broil for 2-4 minutes.