Place the cold water (or unsweetened coconut milk or raw milk) into a saucepot. Sprinkle the gelatin over the liquid and whisk together. Allow to sit for 5 minutes to bloom the gelatin.
After the gelatin has bloomed, heat the mixture over medium high heat until simmering, while whisking often.
Place the gelatin mixture into the bowl of a stand mixer (you can do this in a large bowl with a hand mixer but it will take 15-20 minutes). Add the collagen, allulose and salt, extract and stevia glycerite if using. Place the stand mixer on high and beat for 10 minutes or until the mixture is light and fluffy. NOTE: Do not over whip the mixture or you will end up with lumpy bumpy marshmallows. The mixture should still be liquidy yet very thick.
Place the mixture into a parchment lined casserole dish and put in the fridge for the marshmallows to set. Slice and Enjoy!
Store marshmallows in an airtight container in the fridge for up to 7 days.