Grease an 8 x 8 inch cake pan with butter and line it with parchment paper.

Add freeze dried berries to a food processor and blend until they become a coarse powder.

Melt butter in a large pot or Dutch oven on medium-low heat, about 1 to 2 minutes.

Add marshmallows, reduce heat to low, and cook until smooth (about 3 to 4 minutes) stirring occasionally with a silicone spatula or spoon. Be patient, you don’t want the marshmallows to caramelize or burn.

Remove from heat and mix in the vanilla and the salt, then stir in the powdered freeze dried fruit until fully incorporated.

Mix in the cereal, being sure to do so quickly before the marshmallows cool too much.

Pour the marshmallow cereal mixture into the prepared pan and lightly press into an even layer. You can do this with your hands, a spoon, or a piece of parchment paper placed on top of the marshmallow treats.

Cut these treats into large squares or bite-sized snacks and serve at room temperature.