Preheat oven to 425 degrees.
Put the dry ingredients in a large bowl and whisk together. Make a well in the center of the dry ingredients and add the buttermilk, eggs, and butter, which have been combined separately. Mix wet and dry ingredients thoroughly.
In a bowl toss the blueberries with the lemon juice and sugar and put the mixture in a 9x12 baking dish.
Dollop the batter by spoonfuls around the edges of the dish, but not too close to the edge. This crust expands.
Bake for 45 minutes until the dough is golden brown. Serve with whipped cream or ice cream.
This recipe says it serves 8, but I think it will serve 10-12.