Line a 13x9 inch baking pan with foil, allow foil to extend over edge. Lightly butter with foil.
In a large stockpot or dutch oven melt butter over low heat.
Add marshmallows; cook and stir until melted.
Stir in marshmallow cream, vanilla, and salt.
Stir in green coloring to the remaining mixture.
Reserve one cup of the marshmallow mixture and set aside.
Gently stir rice cereal into the remaining marshmallow mixture.
Transfer cereal mixture to the prepared pan; use spatula sprayed with non stick spray to gently press mixture into pan.
Coat an offset spatula with nonstick spray and pour the reserved 1 cup marshmallow mixture over the top of the cereal mixture; top with the green sugar.
Weigh mixture down by placing a piece of buttered wax paper on top of marshmallow treats and add another 9x13 pan or larger on top of the wax paper and place a couple cans of unopened food on top to add the extra weight and let stand overnight like that.
Using foil edges, gently lift bars out of pan and cut using a buttered knife.
Cut into 24 bars and using the tube of red coloring draw hearts on each bar.