Grind graham crackers in food processor until fine crumbs. Melt butter and poor over graham crackers. Mix with fork tIll moist. Press into 9" pan and place in fridge while preparing lemon filling. Combine condensed milk and eggs, mix till smooth. Add lemon juice and zest; stir well and pour into crust. Bake 15 min. and cool completely. For best flavor serve chilled. One piece per serving. t.