Raspberry Streusel Bars

1. Adjust oven rack to middle position and heat oven to 375 degrees. Make foil sling by folding 2 long sheets of aluminum foil so that they are as wide as 13 by 9-inch baking pan (one 13-inch sheet and one 9-inch sheet). Lay sheets of foil in pan perpendicular to one another, with extra foil hanging over edges of pan. Push foil into corners and up sides of pan, smoothing foil flush to pan. Grease foil and set aside.
2. Using stand mixer fitted with paddle, mix flour, granulated sugar, and salt at low speed until combined, about 10 seconds. Add 16 tablespoons butter, 1 piece at a time; then continue mixing until mixture resembles damp sand, 1 to 1-1⁄2 minutes. (If using food processor, process flour, granulated sugar, and salt until combined, about 5 seconds. Scatter 16 tablespoons butter pieces over flour mixture and pulse until mixture resembles damp sand, about 20 pulses.)
3. Measure 1-1⁄4 cups flour mixture into medium bowl and set aside; distribute remaining flour mixture evenly in bottom of prepared baking pan. Using flat-bottomed measuring cup, firmly press mixture into even layer to form bottom crust. Bake until edges begin to brown, 14 to 18 minutes.
4. While crust is baking, add brown sugar, oats, and pecans to reserved flour mixture; toss to combine. Work in remaining 2 tablespoons butter by rubbing mixture between fingers until butter is fully incorporated. Pinch mixture with fingers to create hazelnut-size clumps; set streusel aside.
5. Combine preserves, raspberries, and lemon juice in small bowl; mash with fork until combined but some berry pieces remain.
6. Spread filling evenly over hot crust; sprinkle streusel topping evenly over filling (do not press streusel into filling). Return pan to oven and bake until topping is deep golden brown and filling is bubbling, 22 to 25 minutes, rotating pan halfway through baking. Let cool to room temperature on wire rack, 1 to 2 hours; remove bars from pan using foil. Cut into squares and serve. (Bars are best eaten the day they are baked but can stored at room temperature for up to 3 days; crust and streusel will soften slightly.)

STRAWBERRY STREUSEL BARS
Thawed frozen strawberries will also work here.
Substitute strawberry jam and chopped fresh strawberries for raspberry jam and raspberries.

BLUEBERRY STREUSEL BARS
Thawed frozen blueberries will also work here.
Substitute blueberry jam and fresh blueberries for raspberry jam and raspberries.