Use a medium or large round crockpot. Coat the cooker with butter flavored nonstick spray or grease with butter. Combine the blueberries, 1/2 c. sugar, water and tapioca in the cooker, stir gently to evenly coat the berries. Cover and cook on LOW until the berries have formed a thick sauce, about 5 hrs.
To make the topping, in a medium bowl whisk together the flour, 2 Tsp of sugar, baking powder, and salt. Using a pastry blender or 2 knives, cut in the butter until the mixture resembles coarse meal. In a small bowl, beat the milk and egg together. Stir egg mix into flour mix to form a soft dough.
Turn the cooker to HIGH and remove the lid. Drop the dough by heaping tablespoonfuls on top of the hot blueberries. Cover and cook until the topping is firm and toothpick inserted comes out clean, about 30 minutes. The topping will not brown.
Turn the cooker off, remove the lid, and let it rest for 10 mins. Wonderful like that or even better over vanilla ice cream!!