01 -
Cut cold butter into small cubes or grate using a box grater. In a large bowl, combine flour, oats, granulated sugar, brown sugar, baking powder, salt, and cinnamon. Add the cold butter and blend with a pastry cutter or fork until the mixture forms pea-sized crumbs. Chill the crumble mixture in the refrigerator for at least 30 minutes.
02 -
If using fresh strawberries, rinse and drain thoroughly; if using frozen, thaw completely and drain excess liquid. In a saucepan over medium heat, combine strawberries, granulated sugar, brown sugar, lemon juice, lemon zest, strawberry jam, and cornstarch. Bring to a gentle boil, then reduce heat and simmer, stirring, until thickened to a jam-like consistency, about 5–7 minutes. Set aside to cool slightly.
03 -
Preheat oven to 175°C (350°F). Line a 20 x 20 cm (8-inch) square baking pan with parchment paper. Press about two-thirds of the chilled crumble mixture evenly into the base of the pan to form the crust. Bake the crust for 10–12 minutes, until pale golden.
04 -
Spread the prepared strawberry filling evenly over the baked crust. Sprinkle the remaining crumble mixture evenly on top of the filling.
05 -
Return pan to the oven and bake for 30–35 minutes, or until crumb topping is golden brown and filling is bubbling at the edges.
06 -
Allow bars to cool completely in the pan. For cleaner slices, chill in the refrigerator or freezer for 15 minutes before cutting. Slice into squares or bars.