In a large saucepan, melt ¼ cup vegan butter over low heat. Once melted, add 4 cups of vegan mini marshmallows, stirring continuously for about 5-7 minutes until fully melted and smooth. Incorporate 1 teaspoon of vanilla extract and gradually mix in green gel food coloring until your desired festive shade is achieved.

Remove the saucepan from the heat and gently fold in 6 cups of puffed rice cereal with a silicone spatula. Ensure that all the cereal pieces are evenly coated with the marshmallow mixture.

Lightly grease a 9x13-inch baking dish with cooking spray or vegan butter. Transfer the cereal mixture into the dish and press it firmly into an even layer, ensuring it reaches all corners. Let the mixture cool for about 10-15 minutes.

Use a sharp knife or cookie cutter to cut or shape the treats into Christmas tree shapes. For a fun presentation, insert gluten-free pretzel sticks into the bottom of each tree.

Sprinkle vegan sprinkles or additional decorations over the shaped treats while they are still slightly warm.

Allow the decorated treats to set completely at room temperature for about 30 minutes. Slice them into individual servings if desired. Store in an airtight container at room temperature for up to 5 days.