In a small bowl, stir together the brown sugar and cinnamon. Dip each biscuit quarter in the melted butter, then in the brown sugar mixture. Place in a single layer on the bottom of the baking dish with all the pieces.
Add 1/2 cup of oats on top of the biscuit pieces.
Toss the blueberries with the granulated sugar. Add half the blueberries on top of the oats. Repeat with the remaining 1/2 cup of oats and remaining blueberries. Drizzle any leftover butter on top.
Bake for 30-40 minutes or until biscuits are cooked through and golden brown. Serve warm.