Heat oven to 375°F. Spray 9-inch square baking pan with cooking spray. Break up three-fourths of cookie dough into pan. With floured fingers, press dough evenly in bottom of pan to form crust. Bake 15 to 20 minutes or until golden brown.
Meanwhile, in medium bowl, crumble remaining cookie dough. Add oats, brown sugar and cinnamon; toss. Set aside.
In small bowl, stir together granulated sugar, cornstarch and lemon juice. Gently stir in blueberries. Sprinkle blueberry mixture evenly over crust. Crumble oat mixture over blueberry mixture.
Bake 30 to 40 minutes or until topping is golden brown and filling is bubbly. Cool 1 hour before serving. Cut into squares.