You don't have to use only blueberries, this works well with fresh raspberries, cranberries, peaches, pears and apples & cinnamon. You can be as creative as you like. Just add a little sharpness to the fruit, in this recipe I added lemon zest, lime or orange juice works fine too :)
1Preheat oven at 375F
Either grease or line a 9x9 square baking pan with parchment paper (I ran out of parchment paper and what i did was use is an old tip my mother used to do and that is to take any brown paper bag, cut it to fit your pan, and submerge the paper in water before placing it in your pan (this trick is also what i use to make crispy meringue bites ;)
*I never add sugar to fruit filling as they are naturally sweet and the crumble has enough sugar, however if you prefer adding sugar, by all means do as you wish :) (some will add between 1/2 cup to 1 cup of sugar)
Mix cornstarch and juice together, mixing well and remove all lumps, stir in blueberries and set aside :)
In large bowl and using your fingers, crumb the flour, oats. butter, cinnamon and salt together until it resembles rough breadcrumbs, add the lemon zest and mix in the beaten egg. Divide it in 2 equal parts.
Press the first half into the base of the baking pan, Add the blueberry mixture and sprinkle over the remaining crumbs
Bake 25 mins or until the crumble is golden brown with a few blueberries peaking through.
If you wish to eat this warm, serve immediately with a good scoop of vanilla bean ice cream or if you want to eat these cold, leave them in pan for a couple hours or until cooled. Cut in bars or slices.