Like a peach pie but easier to share and transport! These bars with a press-in shortbread crust are just the thing for a summer potluck or picnic.
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.
Crust: Beat butter with sugar in a bowl until light and fluffy, about 3 minutes. Scrape down bowl. Add flour and salt; beat until dough forms clumps but does not completely hold together. Press 2 1/2 cups flour mixture into bottom and 1 inch up sides of prepared pan.
Filling: Stir together peaches, sugar, flour, lemon juice, and salt in a bowl. Pour into crust. Crumble remaining flour mixture evenly over top, squeezing to create clumps. Bake until bubbling in center and crust is golden, about 1 hour, 10 minutes (if browning too quickly, tent top with foil). Let cool 20 minutes. Remove from pan and let cool completely on a wire rack, about 1 hour. Cut into 2-inch squares.
Store the bars in the refrigerator, wrapped in plastic or in an airtight container, for up to three days.