Fill a large bowl with ice to use later as an ice bath. Place an empty bowl on top of the ice. Set aside. Place a storage container in the freezer to chill.
Whisk dextrose, guar gum, and locust bean gum powders in a small mixing bowl.
Cook milk in a heavy bottom saucepan over medium heat until it reaches 105°F (40°C) on an instant read thermometer. Once it reaches temperature, whisk in granulated sugar and nonfat milk powder. Once dissolved, whisk in dextrose mixture.
Continue cooking the gelato base over medium heat, stirring often to ensure it doesn’t burn, until it reaches 195°F (90°C) on an instant read thermometer.
Remove saucepan from heat. Whisk in heavy cream.
Place a fine mesh strainer over the empty bowl on top of the ice bath. Strain gelato base.
Chill gelato base until it has stopped steaming. Press plastic wrap against the surface of the gelato (to prevent a skin from forming on top), then cover with plastic wrap and rest in the refrigerator for 24 hours.
Remove the gelato base from the refrigerator, and whisk to reincorporate. Pour the gelato base into an ice cream maker, and process for about 20–25 minutes or according to the manufacturer's directions. The gelato will be on the soft side.
Transfer churned gelato into chilled storage container. Place gelato into the freezer to "cure" or harden up for a few hours. To serve, swipe the frozen gelato with a flat paddle. Smash the gelato on the side of the storage container to push out some of the air. Transfer to a serving bowl.
Store gelato in an airtight container in the freezer for up to 2 weeks.