Preheat oven to 375 degrees F. Add blueberries to a 9 by 9 by 2-inch baking dish, or an 11 by 7 by 2-inch baking dish. Drizzle with lemon juice.
In a small bowl, whisk 1/3 cup granulated sugar with 2 Tbsp flour, sprinkle mixture over blueberries and toss. Bake in preheated oven until filling is hot and edges are bubbling, about 25 minutes.
Meanwhile, prepare topping. In a medium mixing bowl whisk together 1 cup flour, 1/4 cup sugar, baking powder, baking soda, salt and cinnamon, make a well in center.
In a separate mixing bowl, whisk together buttermilk, butter and vanilla. Just a minute before you pull the filling from the oven pour buttermilk mixture into flour mixture and fold just until combined and there's no longer streaks of flour.
Remove hot filling from oven, increase oven temperature to 400, and immediately dollop spoonfuls of batter (I used a cookie scoop but two spoons will work) over blueberry filling about the side of a golf balls.
Sprinkle sugar over dough then return to oven and bake until filling is bubbling again and biscuit topping is cooked through (it shouldn't be doughy) about 12 - 14 minutes. Serve warm with vanilla ice cream.
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