Lightly coat a 2-quart rectangular baking dish with cooking spray; set aside. In a large bowl stir together pastry flour, cornmeal, granulated sugar, 1 teaspoon of the cinnamon, the baking soda, salt, and the 1/2 teaspoon ginger.
In a medium bowl whisk together yogurt, eggs, oil, applesauce, and butter flavoring until well mixed. Add egg mixture to the flour mixture, stirring just until combined. Pour half of the batter into the prepared dish, spreading evenly.
Sprinkle with 1 cup of the frozen blueberries. Top with the remaining batter, spreading evenly. Cover and chill for 8 to 24 hours.
Allow the coffee cake to stand at room temperature while the oven preheats to 350 degrees F. In a small bowl toss together the remaining 1 cup frozen blueberries, the brown sugar, and the remaining 1/2 teaspoon cinnamon; sprinkle over the batter. Bake, uncovered, about 35 minutes or until a wooden toothpick inserted near the center comes out clean. Serve warm. If desired, serve with whipped topping and sprinkle with additional ginger.