A family recipe for rhubarb crunch with loads of rhubarb and a thick, crumbly oat layer.
Mix the bottom layer/topping ingredients in a bowl until crumbly. Press 1/2 to 3/4 of the mixture into a greased 8" pan.
Cover with chopped rhubarb.
Make the syrup: Put just a portion of the water into the cornstarch and mix - this will prevent lumps. Then add the remaining water, sugar and vanilla. Heat on the stovetop over medium heat until the liquid begins to thicken into a syrup. About 5 -8 min.
Pour about three quarters of the syrup over the rhubarb (see Notes). Top with remaining crunch topping.
*This recipe is super sweet - I would suggest cutting back on the sugar within the crunch and I only used 3/4 of the syrup.