Step 1: In a medium saucepan, combine the heavy cream, whole milk, granulated sugar, and salt.
Step 2: Heat the mixture over medium heat, stirring constantly, until the sugar is completely dissolved. Do not boil. Remove from heat.
Step 3: Stir in the vanilla bean paste (or vanilla extract/seeds). Taste and adjust sweetness if desired, keeping in mind that cold flavors are less pronounced.
Step 4: Pour the mixture evenly into two Ninja Creami pint containers. Ensure the mixture level is below the MAX fill line.
Step 5: Place lids on the pints and freeze them on a level surface for at least 18-24 hours, or until completely solid. Freezing overnight is ideal.
Step 6: Once frozen solid, remove one pint from the freezer and remove the lid. Place the pint into the outer bowl of your Ninja Creami.
Step 7: Install the paddle into the outer bowl lid and lock the lid onto the outer bowl. Place the outer bowl assembly into the Creami machine.
Step 8: Select the 'ICE CREAM' function. The machine will process the frozen mixture.
Step 9: After the first spin, check the consistency. If it's crumbly or powdery, add 1-2 tablespoons of cold whole milk (or cream) and select the 'RE-SPIN' function.
Step 10: Continue re-spinning, adding a tablespoon of liquid each time, until you reach your desired creamy, scoopable consistency. This often takes 1-2 re-spins. For mix-ins, create a 1-inch wide hole down the center of the pint, add your desired mix-ins, and select the 'MIX-IN' function.
Step 11: Serve immediately and enjoy! Store any leftovers in an airtight container in the freezer. If refrozen solid, you may need to re-spin before serving again.