• Preheat the oven to 375. Line an 8x8 baking pan with parchment paper so it hangs over the edges (so you can lift out your bars). Set aside.
• In a medium bowl or stand mixer, blend the flour, sugar, salt if using; stir to combine. Add the butter and blend until a soft dough forms. If your butter is too cold it will only crumble into the dough. If this happens, add the water a tablespoon or two at a time until the dough comes together. Set aside 1/3 cup of this dough for your crumble topping.
• Press the remaining dough into your pan in an even layer. I find it easier to drop big spoonfuls in the pan and the press them into an even layer.
• Bake untill the edges brown lightly and the base is firm and set in the center. 14-16 minutes maybe; mine took closer to 20.

Make the jam layer and the crumble

• While the base bakes, mix the jam, berries and lemon and mash with a fork. Leave a few pieces of raspberries in chunks. Set aside.
• In a small bowl blend the remaining sugar, pecans, oats and cookie base to make a chunky crumble. Set aside.

Put it together

• Pour the berry mixture over the hot base. Spread evenly. Break the crumble in to pieces, leaving some berries showing through and bake 25-28 minutes until the berries thicken and bubble and the crumble is golden brown.
• Cool in the pan 10 minutes then lift out and cut in to squares when cool. Store at room temperature 1-2 days.