Plum-and-Blackberry Cornmeal-Almond Crumb Bars

Crust:

Preheat oven to 375 degrees. Butter an 8-by-8-by-2-inch cake pan. Line with parchment, leaving a 2-inch overhang on two sides; butter parchment. Spread almonds in a single layer on a baking sheet; toast until golden brown and fragrant, about 10 minutes. Let cool 15 minutes, then coarsely chop. Whisk together flour, cornmeal, and salt.

Beat butter with sugar on medium-high speed until light and fluffy, about 3 minutes. Scrape down bowl. Add flour mixture; beat until dough forms clumps but does not completely hold together. Press 3 cups of dough mixture into bottom and 1 inch up sides of prepared pan. Stir almonds into remaining dough mixture.

Filling:

Stir together plums, blackberries, sugar, flour, lemon juice, pepper, and salt. Pour into crust. Crumble remaining crust mixture over top, squeezing to create clumps. Bake until bubbling in center and crust is golden, 1 hour to 1 hour, 10 minutes (if browning too quickly, tent with foil after about 50 minutes). Let cool 1 hour. Remove from pan and transfer to a wire rack; let cool completely, about 2 hours. Cut into squares.