Adapted from Martha Stewart’s Baking Handbook
Makes 12 squares of roughly 3 x 3-inches
2 sticks unsalted butter, room temp, cut into pieces, plus more for buttering the pan
1 1/2 cups blanched (skinless) almonds, very finely ground in a food processor
2 cups all purpose flour
1/2 cup plus 1/3 cup granulated sugar
1 tsp salt
1 1/2 cups raspberry (or apricot or blackberry or strawberry or…) jam
Preheat the oven to 350°F and arrange a rack in the middle of the oven. Generously butter at 9 x 13-inch baking pan.
Whisk together the ground almonds, flour, sugar and salt in a large mixing bowl. Using a pastry blender, cut in the butter, working until the mixture resembles coarse crumbs. Transfer half of the flour mixture to the prepared baking pan, and press it evenly over the bottom of the pan. Bake until lightly golden, about 15 minutes, rotating the pan half-way through. Transfer to a wire cooling rack and cool completely.
Evenly spread the jam over the cooled crust. Sprinkle the remaining crumb mixture over the jam filling, gently squeezing handfuls of the mixture, then crumbling it into coarse pieces, spreading the crumbs evenly over the jam.
Bake until the topping just begins to turn lightly golden, about 20 minutes, rotating the pan half-way through. Transfer to a wire cooling rack to cool completely.
Using a sharp knife, trim around the edges of the pan. (The crusty edge is a good snack.) Slice the inner rectangle in to twelve roughly 3 x 3-inch squares. The raspberry bars can be kept in an air-tight container at room temperature for up to four days.