Heat raspberries, vanilla, sugar, and cornstarch over medium heat for 5-10 minutes or until raspberries have broken down and thickened. If sauce seems watery, add another teaspoon of cornstarch.
Oat Layer:
Preheat oven to 350°F. Line a 8x8" baking dish with parchment paper, set aside.
In a medium mixing bowl, combine flour, oats, salt, sugar, and brown sugar. Stir in melted butter until a crumble like consistency.
Assembly:
Pour half of oatmeal layer into bottom of prepared baking dish. Press firmly to create a crust.
Pour raspberry sauce over oatmeal layer and spread evenly.
Sprinkle remaining oatmeal topping over raspberry layer.
Bake for 27-30 minutes or until topping is golden and raspberry sauce has set.Allow to cool completely before cutting into squares.