Grease the bottom and sides of an 8x8 inch baking dish with butter and set aside.
In a large saucepan, melt the butter over low heat until it’s fully melted and begins to bubble gently, filling the air with a rich buttery aroma.
Add the marshmallows to the melted butter and stir continuously with a spatula until they are completely melted and the mixture is smooth and glossy. You’ll hear a gentle bubbling and see the marshmallows disappearing into a shiny pool.
Stir in the pureéd pumpkin along with the cinnamon, nutmeg, and ginger until evenly combined—this will deepen the aroma and give the mixture a warm, orange hue.
Remove the mixture from heat and immediately pour it over the rice cereal in a large mixing bowl.
Gently fold the cereal into the marshmallow mixture, mixing well until each piece is coated evenly and the mixture is thick and sticky.
Transfer the coated cereal mixture into the prepared dish and press down firmly with a spatula or your greased hands to create an even layer.
Let the treats sit at room temperature for at least 15 minutes to firm up, allowing the marshmallow glue to set and the shapes to stabilize.
Once cooled and firm, cut into squares or bars. Enjoy the vibrant, spiced aroma and crispy-chewy texture of these festive treats.
