Spray a 13-by-9-inch baking pan with nonstick cooking spray.
Pulse the freeze-dried strawberries in the bowl of a food processor until very coarsely chopped. If you don't have a food processor, you can do this with a rolling pin using a zip-top bag.
Melt the butter in a large pot over medium heat. Quickly stir in the marshmallows and cook until completely melted. Add the chopped strawberries, combine with the mixture and remove from the heat. Stir in the cereal until well-coated and combined. Spray a rubber spatula or wooden spoon with nonstick cooking spray and press the mixture evenly into the prepared pan. Let cool until set.
With the assorted heart cookie cutters, cut out different heart shapes.