Prepare your pan by greasing a 9x13 inch (23x33 cm) baking dish or lining it with parchment paper for easy removal.
In a large pot or heavy skillet, melt the vegan butter over low heat.
Add the mini vegan marshmallows and stir continuously until they are completely melted and smooth. Be careful not to overheat, as this can make the final treats hard.
Remove the pot from the heat immediately.
Pour in the crisp rice cereal and use a spatula to gently fold everything together until the cereal is evenly coated in the marshmallow mixture.
Transfer the mixture to your prepared pan.
Using a greased spatula or a piece of wax paper, gently press the mixture into an even layer.
Don't press too firmly, or the squares will be dense and hard.
Allow the treats to cool completely at room temperature for at least 1 hour, or in the refrigerator for 30 minutes if you're in a hurry.
Once set, cut into 24 squares and serve.
Don't press the mixture into the pan too hard. A gentle, even pressure is all you need to create a chewy, airy texture. Compacting it will result in dense, tough squares.
