Meanwhile, heat oven to 350°F. Line 9-inch square pan with foil; spray foil with cooking spray. In food processor, place flour, 1/2 cup sugar, 1/2 cup butter and 1/4 teaspoon salt. Cover; process, using quick on-and-off motions, until mixture looks like coarse meal. Add egg yolks. Cover; process, using quick on-and-off motions, just until dough comes together. Press dough in bottom of pan. Sprinkle with pretzels, pressing lightly into dough.