In a large pot, one you will be able to fit all 8 cups of cereal in, heat the vegan butter on medium.
Once the butter has melted, add the vegan marshmallows, and stir to combine.
Reduce the heat to low, and continue to stir frequently until the marshmallows have melted and are fully combined with the butter. This may take 5-7 minutes or so.
Then pour in the molasses, vanilla, ginger, cinnamon and cloves. Stir to fully combine everything.
Turn off the heat and immediately pour all the rice cereal into the pot. Stir to combine and coat all the cereal evenly with the marshmallow mixture.
Next, scoop all of the rice krispie treat mixture into a 13x9 inch rectangular baking dish that has been sprayed with non-stick spray or lined with parchment paper.
Now, press the rice krispie treats down into the pan evenly. It will be very sticky at this point, so I take a piece of parchment paper and lay it over the top of the mixture and use that to press it all down so it is flat and even.
Chill for at least an hour, but they keep well in the fridge for about a week.
Before serving, top with melted white chocolate, or extra cinnamon if desired. Cut into squares and serve.