Blueberry rhubarb cornmeal biscuit cobbler. First, make biscuits with 1 cup flour, 1 cup cornmeal, sugar, baking soda, baking powder, salt. Cut in 8 tablespoons of butter until it resembles coarse cornmeal. Add buttermilk until batter comes together. Scoop onto baking sheet and bake until golden and puffed. Meanwhile, toss blueberries and chopped rhubarb with the lemon juice, lemon zest, sugar, and cornstarch. Place fruit in deep pie plate or dish and bake covered until juices are bubbling (45 min at 375 for me) Put biscuits on top and heat for another 5 minutes.