I just made some of these to send to my daughter who is going to school in England. I just thought that the marshmallows would help hold in the moisture but I don't really know it for a fact. I think that the idea of vaccuum packing them would work well. Unfortunately, I had already sent the Rice Krispies Treats when I read that. Most people have the recipe but I'll post it anyway. It is also on the box of Rice Krispies and on the package of Kraft Jet Puffed Marshmallows. There is also a recipe, which is very similar, that used to be on the Cheerios box. I looked & could nor find the recipe and I don't happen to have any Cheerios. Maybe someone else will post it or you might be able to find it on the Cheerios box. It uses marshmallows and peanut butter so it is a bit different. I have made them and they are good as well.

Rice Krispies Treats

3 Tbl. butter or margarine
1 package (10 oz., about 40) regular marshmallows or 4 c. miniature marshmallows
6 c. Kellog's Rice Krispies

Stove top:
1. Melt margarine in saucepan over low heat. Add marshmallows and stir until completely melted. Remove from heat.

2. Add Rice Krispies cereal. Stir until well coated.

3. Using buttered spatula or wax paper, press mixture evenly into 13" X 9" X 2" pan coated with cooking spray or greased with margarine or butter. Cut into 2 inch squares when cool.

Microwave:
In a microwave-safe bowl, heat margarine and marshmallows at high for 3 min., stirring after 2 min. Stir until smooth. Follow steps 2 and 3 above.