In large saucepan, melt butter over low heat. Add marshmallows and stir until completely melted. Remove from heat.

Add Cocoa Krispies cereal and crushed graham crackers. Stir until well coated.

Using buttered spatula or wax paper, evenly press mixture into 13 x 9 x 2-inch pan coated with cooking spray. Cool.

Cut into squares and enjoy. (Best if served the same day.)