Line a 13 by 9-inch pan with aluminum foil, making sure it extends over the sides. Very lightly spray or butter the foil.
To make the crust, combine the flour, butter, brown sugar, and salt in a food processor fitted with a metal blade. Pulse until the butter forms pieces the size of small pebbles, 20 to 30 seconds. Pour the crust crumbs into the prepared pan and press down to form an even layer. Cover and refrigerate for at least 30 minutes, or up to overnight.
Preheat the oven to 350°F.
Bake the crust until golden, about 25 minutes. Set aside to cool.