Preheat the oven to 350°F (175°C). Grease the bottom and sides of an 8x8 inch baking pan with butter or non-stick spray.
In a mixing bowl, combine 1 cup of flour and 1/2 cup of granulated sugar. Add the cold, cubed butter and use a pastry cutter or your fingers to mix until the mixture resembles coarse crumbs with some larger pea-sized pieces.
1 cup all-purpose flour
Press two-thirds of the crumb mixture evenly into the prepared baking pan to form the crust. Spread the strawberry jam evenly over the crust, leaving about 1/4 inch border around the edges.
1 cup all-purpose flour
Sprinkle the remaining crumb mixture over the jam layer, gently pressing down to help it adhere. Finish by sprinkling a pinch of sea salt evenly on top.
1 cup all-purpose flour
Bake in the preheated oven for 25-30 minutes, or until the crumble topping is golden brown and bubbly at the edges. Once done, remove from the oven and let cool in the pan for at least 15 minutes before slicing.
Cut into squares, serve slightly warm or at room temperature. The bars should have a crunchy topping, a slightly sticky jam layer, and a tender crust underneath.
