Preheat oven to 375°.
Combine first 4 ingredients in a medium bowl; spoon into an 11 x 7-inch baking dish. Lightly spoon flour into a dry measuring cup, and level with a knife. Combine 2/3 cup flour, 1/2 cup brown sugar, oats, and cinnamon, and cut in the butter with a pastry blender or 2 knives until the mixture resembles coarse meal. Sprinkle over the blueberry mixture. Bake at 375° for 30 minutes or until bubbly. Top each serving with 1/4 cup frozen yogurt.
Note: Topping may also be made in the food processor. Place 2/3 cup flour, 1/2 cup brown sugar, oats, and cinnamon in a food processor, and pulse 2 times or until combined. Add butter; pulse 4 times or until mixture resembles coarse meal.