Make the dough:
Preheat the oven to 340°F/170°C.
Line the pan with parchment paper. Set aside.
Put the flour, sugar, vanilla extract and salt in a food processor. Process in short pulses until it becomes a crumbly mixture.
Add the butter and process until the mixture looks like coarse breadcrumbs.
Scoop out 3/4 cup of the crumbs. Set aside.
Add water to the food processor and process until a uniform dough is obtained.
Press the dough into the prepared pan to form the bottom crust.
Place the dough in the freezer for 20 minutes.
Spread the filling over the crust.
Top with remaining crumb mixture.
Bake for 25 to 35 minutes until golden. Cool completely before slicing into small bars.
Keep in an airtight container for up to seven days.