Preheat your oven to 350°F (175°C) and line an 8-inch square baking pan with aluminum foil.

Melt ½ cup of unsalted butter in a mixing bowl. Add 1 cup of all-purpose flour, 1 cup of old-fashioned oats, ½ cup granulated sugar, ½ cup light brown sugar, and a pinch of salt. Stir until sandy.

Reserve 1 cup of the crumb mixture for topping and press the remaining into the prepared pan.

In another bowl, combine 2 cups coarsely chopped fresh strawberries, 2 tablespoons granulated sugar, 1 tablespoon lemon juice, and 1 tablespoon cornstarch. Toss gently to coat the strawberries.

Spread the strawberry mixture over the crust evenly.

Sprinkle the reserved crumble mixture over the strawberry filling.

Bake in the preheated oven for approximately 50 minutes until golden brown.

Allow to cool at room temperature for at least 1 hour before lifting out and slicing into squares.