Delicious raspberry bars when you have a really good jar of jam.
Heat oven to 375 degrees. Line bottom of pan with foil and spray foil with nonstick cooking spray.
Mix flour, granulated sugar and salt with low speed until combined for 5 seconds. On low, add butter a tablespoon at a time. Mixture should resemble damp sand.
Measure 1.25 c above mixture into medium bowl and set aside. distribute remaining flour mixture evenly in bottom of prepared baking pan; press mixture into an even layer to form a bottom crust. Bake until edges begin to brown 14 to 18 minutes.
Create streusel: Add brown sugar, oats, and nuts to reserved flour mixture; toss to combine. Work in remaining 2 tbsps butter by rubbing mixture between fingers until butter is fully incorporated.
Combine preserves, raspberries and lemon juice in small bowl; mash with fork until combined but some berry pieces remain.
Spread filling evenly over hot crust; sprinkle streusel topping evenly over filling. Bake for 22-25 minutes.
Cool to room temperature and remove from baking pan. Cut into squares with a chef's knife.