Preheat oven 350F
Line a 9 x 13 pan with parchment paper, extendng over edge of pan. Coat lightly with cooking spray
COMBINE graham cracker crumbs and butter; mix well. Press crumb mixture firmly into bottom of prepared pan.
Pour sweetened condensed milk evenly over crumb mixture.
BAKE 25 to 30 minutes or until lightly browned.
Loosen from sides of pan while still warm; cool on wire rack.
After bars have baked and cooled, lift up by edges of foil to remove from pan. Cut into individual bars.