Prepare your workspace:Line two baking sheets with parchment paper or silicone baking mats. Set out a bowl of water or nonstick spray for your hands (to prevent sticking when shaping the wreaths).
Melt the butter and marshmallows:In a large pot, melt the butter over low heat. Add the marshmallows and stir constantly until completely melted and smooth.
Add vanilla and food coloring gel:Stir in the vanilla extract and green food coloring gel until the mixture is evenly colored. The gel creates a bright and festive green.
Mix with cornflakes:Remove the pot from the heat and gently fold in the cornflakes until they are evenly coated with the green marshmallow mixture.
Shape the wreaths:Working quickly, drop spoonfuls of the mixture onto the prepared baking sheets. Spray your hands with cooking spray or dip in a little water to prevent them from sticking. Use your hands to shape each mound into a wreath, pressing gently to flatten slightly and making a hole in the center with your fingers.
Decorate with cinnamon imperials:While the wreaths are still sticky, press cinnamon imperials onto each one to resemble holly berries.
Cool and set:Allow the wreaths to cool completely at room temperature. Once set, transfer them to an airtight container for storage.