1 1/2 cups Old-fashioned rolled oats.
1/2 cup flour
1/2 cup light brown sugar, packed
1/2 teaspoon baking powder
6 tablespoons butter, melted
Filling:
2 cups blueberries, rinsed and picked over
3 tablespoons sugar
2 teaspoons cornstarch
1/2 teaspoon cinnamon
1 teaspoon lemon juice
Directions:
Preheat oven to 350ºF. Line an 8-inch square pan with foil, making sure the foil hangs over the edges for easy removal of the bars later on. Spray the foil lightly with cooking spray.
In a bowl, mix the oats, flour, brown sugar and baking powder together. Add the melted butter and mix well until thoroughly combined. Press half of the crumb mixture into the bottom of the lined pan. Bake for 12 minutes.
Meanwhile, combine the blueberries, sugar, cornstarch, cinnamon and lemon juice in a saucepan over medium heat. Stir occasionally and bring to a gentle simmer. Simmer for about 2 minutes, or until the liquid does not seem so cloudy, and has thickened nicely.
Spoon the blueberry mixture over the bottom crust, spreading very gently to the edges.
Top the blueberry mixture with the remaining half of the crumb mixture- spreading it evenly.
Bake in a 350ºF oven for 30 minutes. Remove from the oven and allow to cool completely before removing from the pan.
For best results, chill before cutting.