Lightly grease a 9x13 inch pan. Optionally, lightly grease a 9x9 inch pan (see Recipe Notes below if using a 9x9 inch pan).
Add the freeze-dried strawberries to a food processor or high-powered blender. Pulse until they're fine crumbs.
Add the butter to a very large saucepan. Melt over low heat.
Add in the marshmallows and gently stir with a rubber spatula as the marshmallows melt together with the butter.
When the marshmallows are almost melted, add in the pulsed freeze-dried strawberries. Gently stir as the freeze dried berries dissolve and melt.
Once the marshmallows are completely melted (if you have pieces of strawberries still - that's ok), turn off the burner. Stir in the cereal 1 cup at a time. You want all the cereal covered with gooey marshmallow.
Spoon/pour the mixture into the prepared pan. Lightly grease your hands and gently press the mixture down into the pan. The tighter you pack it down, the firmer your cereal treats will be.
Chop the chocolate into very fine pieces and place in a heatproof bowl.
Microwave the chopped chocolate on medium power (not high power, which is often standard) for 45-second intervals. Stir between each interval until smooth.
Pour the chocolate over the Rice Krispie treats and spread smooth. Let the bars set at room temperature until the chocolate has hardened. Slice with a thin, sharp knife. I always let cereal treats firm up on the counter, instead of in the fridge, because in the fridge they can get too hard.