05When rhubarb and blueberries are softened, use a potato masher to mash and smooth out the larger chunks. Once bigger pieces are broken up, mix in the sugar/cornstarch mixture. Continue to stir until thickened.
06Once mixture is thickened, pour over crust. Top with reserved crust mixture.
07Bake at 350ºF for 30 minutes.
08Tips: 1. Mixing the sugar and cornstarch together will prevent lumps of cornstarch in your mixture. 2. The bars will puff up considerably, so don’t be alarmed when you open the oven to take out the bars. They will be a bit jiggly. That’s OK! They are done! 3. When they cool, they’ll “deflate” a bit and set up nicely.