Make the filling. In a saucepan, bring the blueberries, maple syrup and lemon juice to a boil, reduce the
heat and simmer until tender, about 10 minutes. Whisk the cornstarch with water and whisk into the
blueberries, boil and stir until thickened. Let cool for about an hour. Placing a piece of plastic wrap or
wax paper directly on the blueberry mixture will prevent the filling from forming a skin.
In a large bowl, mix together the oats, flour, brown sugar and salt. With a pastry blender, cut in the
butter until coarse crumbs form. Press half the mixture into an 8 inch square oiled pan, then spread on
the blueberry filling. Sprinkle with the remaining oat mixture and press lightly. Bake in the centre of the
oven until golden brown, approximately 45 minutes. Let cool before cutting into squares.