Preheat your oven to 350°F (175°C). Line a 9×9-inch pan with parchment or foil for easy lifting. Pro move: spray the liner lightly so nothing sticks.

In a bowl, toss berries with lemon juice and sugar. Let them mingle while you do the rest—flavor development without any extra effort.

In another bowl, whisk oats, flour, brown sugar, cinnamon, and salt. Stir in melted butter until the mixture looks like chunky wet sand.

Reserve about 1 cup of the crumble mixture for the top. Press the remaining crumble into the bottom of the pan to form a crust. It should be firm but not rock-solid.

Spread the berry mixture evenly over the crust. Dollop and gently spread so you don’t smear the jam everywhere—precision counts here.

Sprinkle the remaining crumble over the berry layer. If you kept the reserved crumble, crumble it on top like confetti.

Bake 35-40 minutes until the top is golden and the berries are bubbling. Let cool completely before slicing for neat bars.