In a medium saucepan, combine milk, evaporated milk, cream, and sugar. Heat over medium until steaming, but do not boil.
Place the yolks in a medium bowl, then whisk in 1/3 hot milk mixture. Transfer the egg-milk mixture back to saucepan and return to medium heat. Cook, stirring constantly, until mixture coats the back of a spoon, about 12 minutes.
Set a medium bowl in a bowl of ice water, then pour the custard into the empty bowl. Let the mixture stand, stirring occasionally, until cool, about 45 minutes. Transfer the custard to a blender with peanut butter and 1 1/2 teaspoons salt; blend until smooth.
Transfer the custard to a gelato machine and freeze according to manufacturer's instructions, about 45 minutes.
This recipe was provided by professional chefs and has been scaled down from a bulk recipe provided by a restaurant. The Food Network Kitchens chefs have not tested this recipe, in the proportions indicated, and therefore, we cannot make any representation as to the results.