Sprinkle gelatin over water in a small bowl and it set aside to rehydrate.

Add the cream and milk to a large pot on medium heat and bring to a simmer then reduce the heat to low.

Whisk the yolks together with the stevia, salt, and glucomann in a large heat proof bowl.

When the milk and cream are at a low simmer, slowly pour the hot mixture into the egg yolks while whisking constantly to keep the eggs from overcooking to temper them. Then pour the tempered yolks back into the pot of cream. Cook while whisking slowly and constantly until thickened, about 4-5 minutes. As the mixture becomes more thick, whisk vigorously to keep the cooking even, watching for bubbles. When you see a couple of bubbles, remove from heat. Do not boil as it will cause the eggs to overcook and scramble.

Remove from heat and whisk in the rehydrated gelatin until smooth, about 1 minute. Then whisk in the butter, another 30 seconds or so.

Strain the mixture through a fine mesh strainer and into a storage container. Immediately press plastic wrap directly onto the surface of the cream to prevent a skin from forming. Refrigerate until completely cold, about 2 hours and up to 3 days. Whisk thoroughly before using.