Fifteen minutes before baking, place rack in center of oven and preheat to 400 degrees. Have a 6 cup souffle dish or casserole ready. For the biscuit, combine the flour, 2 tablespoons sugar, baking powder, cream of tartar and salt in a food processor or bowl. Work in the butter either with the metal blade or a pastry blender until it resembles a coarse meal. Add the sour cream and process or mix just until the dough clumps together. Transfer to a large plastic food bag and press the dough through the bag into a neat circle the same diameter as the baking dish. Refrigerate as you prepare the fruit. For the fruit, gently toss the peaches with the sugar, tapioca, lemon juice and cinnamon in a 10 inch skillet. Cook, stirring occasionally, just until they reach a simmer, about 4 minutes. Remove from the heat and add the blueberries. Transfer to the baking dish. Place the dough on top of the fruit and gently tuck the edges down. Sprinkle with the remaining 2 teaspoons of sugar. Place an aluminum foil lined baking sheet on a lower shelf. Bake the cobbler until the crust is golden, about 30 minutes. Serve hot or warm, with ice cream if desired. The cobbler is best the day it is made, but it can be reheated. Place in a cold oven, turn it to 350 degrees and bake 12 to 15 minutes.{$7e}(Original recipe for 6)
