Preheat & Prepare
Preheat oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper for easy removal.
Make the Shortbread Crust
In a large bowl, mix flour, sugar, and salt.
Cut in the cold butter using a pastry cutter (or fork) until the mixture resembles coarse crumbs.
Stir in vanilla extract and mix until the dough holds together when pressed.
Press 2/3 of the mixture evenly into the bottom of the pan. Reserve the remaining dough for the crumble topping.
Make the Raspberry Filling
In a bowl, combine raspberry jam, fresh raspberries, and lemon juice.
If using fresh raspberries, stir in cornstarch to help thicken the filling.
Spread the raspberry mixture evenly over the crust.
Add the Crumble Topping
Sprinkle the reserved crumble dough evenly over the raspberry filling.
Bake for 35-40 minutes, or until the top is golden brown and bubbling.
Cool & Slice
Let the bars cool completely in the pan before slicing.
Once cooled, lift them out using the parchment paper and cut into squares.
Serve & Enjoy!
Enjoy as-is or dust with powdered sugar for a bakery-style finish!