In a food processor, pulse 1 cup of the freeze-dried strawberries until they form a powdered texture.
In a large bowl, combine the Rice Krispie cereal, pulsed freeze-dried strawberries, 1/2 cup remaining freeze-dried strawberries, and 1 cup of the mini marshmallows. Stir to combine. Set aside.
In a large pot, melt the butter. Once melted, add the remaining 4 cups of mini marshmallows and stir until completely melted. Remove from heat. Pour the dry ingredients into the marshmallow mixture. With a spatula, mix until everything is well combined and coated.
Pour mixture into a greased 13-in by 9-in pan or onto a sheet of wax paper. With a greased spatula, evenly spread mixture into the shape of the pan. Allow to set before cutting into pieces.