Preheat oven to 350 degrees and spray an 8x8 baking dish with non-stick spray
In a medium sized bowl, combine flour, oats, brown sugar and salt
Add in vanilla and applesauce and continue mixing until uniformly combined
Press about 3/4 of the crumble into the bottom of the baking dish to make the crust layer and bake for 5 minutes
Meanwhile, heat 2 cups of the blueberries in a small saucepan on medium-high heat. Cover for about 2 minutes, then uncover and mash berries, creating more of a “sauce”. Let simmer for 2-5 minutes, until slightly thickened
Spread blueberry sauce on top of crust layer, top with remaining 1/2 cup of blueberries, and top with the remaining crumble mixture
Return to the oven to bake for an additional ~15 minutes
Let cool, cut into 9 squares and enjoy!
Notes
When pressing oat mixture into the baking dish, I recommend wetting your hands with cool water to prevent it from sticking and to more evenly spread