Makes 24 bars
Frozen raspberries can be substituted for fresh, but be sure to defrost them before using. We like the chew of old-fashioned rolled oats here but quick-cooking oats can be substituted.
2½ cups (12½ ounces) all-purpose flour
⅔ cup (4⅔ ounces) granulated sugar
½ teaspoon salt
2¼ sticks unsalted butter, cut into 18 pieces and softened
½ cup (1½ ounces) old-fashioned rolled oats (see note above)
½ cup (2 ounces) pecans, toasted and chopped fine
¼ cup packed (1¾ ounces) light brown sugar
¾ cup raspberry jam
¾ cup (3¾ ounces) fresh raspberries
1 tablespoon fresh lemon juice

1. Adjust an oven rack to the middle position and heat the oven to 375 degrees. Line a 13 by 9-inch baking pan with a foil sling and grease the foil.
2. Whisk the flour, granulated sugar, and salt together in a large bowl. Beat in 16 tablespoons of the butter with an electric mixer at low speed until the mixture resembles wet sand, 1 to 1½ minutes. Reserve 1¼ cups of the mixture for the topping.
3. Sprinkle the remaining mixture into the prepared pan and press into an even layer with the bottom of a measuring cup. Bake the crust until fragrant and the edges begin to brown, 14 to 18 minutes.
4. Mix the reserved flour mixture, oats, nuts, and brown sugar together in a medium bowl. Add the remaining 2 tablespoons butter and pinch the mixture between your fingers into hazelnut-sized clumps of streusel. In a small bowl, mash the jam, raspberries, and lemon juice together with a fork until just some of the berry pieces remain.
5. Spread the berry mixture evenly over the hot crust, then sprinkle with the streusel topping. Bake the bars until the filling is bubbling and the topping is deep golden brown, 22 to 25 minutes, rotating the pan halfway through baking.
6. Let the bars cool completely in the pan, set on a wire rack, about 2 hours. Remove the bars from the pan using the foil, cut into squares, and serve.
To Make Ahead: The cooled, uncut bars can be wrapped in plastic wrap, then foil, and frozen for up to 1 month. Thaw the bars completely at room temperature (do not unwrap), about 4 hours, before cutting and serving.

http://www.americastestkitchenfeed.com/recipes/raspberry-streusel-bars/