Preheat your oven to 350 degrees Fahrenheit. Grease a 9 by 9 inch square baking pan with butter or line it with parchment paper, leaving a slight overhang on the sides to make it easier to lift the bars out later.
In a large mixing bowl, combine the all purpose flour, rolled oats, light brown sugar, baking powder, and salt. Add the cold, cubed butter and the alcohol-free vanilla extract. Use a pastry cutter or your clean fingertips to work the butter into the dry ingredients until the mixture looks like coarse crumbs with some pea-sized pieces of butter remaining.
Take about two-thirds of the crumble mixture and press it firmly and evenly into the bottom of your prepared baking pan. Make sure to press down hard to create a solid base that will hold up the fruit filling. Set the remaining crumble mixture aside for the topping.
In a medium bowl, toss the cranberries with the granulated sugar, cornstarch, orange zest, and orange juice. Stir well until all the berries are evenly coated. Pour this fruit mixture over the pressed base and spread it out into an even layer.
Sprinkle the remaining crumble mixture evenly over the top of the cranberry layer. Do not press it down, just let it sit loosely. Place the pan in the center of the oven and bake for 40 to 45 minutes, or until the top is golden brown and the cranberry filling is bubbling around the edges. Allow the bars to cool completely in the pan on a wire rack before slicing into squares.
