Pour milk and cream (if using) in a small saucepan and sprinkle gelatin over to soften. Let sit for about 5 minutes, then heat slowly over medium-low heat until steaming, but DO NOT BOIL.
Meanwhile, shred cheese and pulse in a food processor with the salt. When the milk is hot, turn on the food processor and with the motor running, slowly pour the milk-gelatin mixture over the cheese and process until completely melted and very smooth, 30-60 seconds. Scrape into prepared pan and cover with plastic wrap.
Chill for at least three hours. Keeps up to one week in the refrigerator.
Notes
If you'll be using this homemade Velveeta in a dip or nacho-like sauce, it will be even easier if you use the homemade Cheez Whiz version of the recipe, which can be found at the same page: https://nourishingjoy.com/homemade-cheez-whiz-homemade-velveeta-real-food/