Making the custard:
In a medium-size bowl, add the egg yolks and sugar; beat until thick and lemon colored; set aside. NOTE: If making Chocolate Ice Cream, add the cocoa powder to the egg mixture now.
In a small heavy saucepan over low to medium-low heat, add milk. Slowly bring milk just to a gentle simmer or until it begins to bubble around the edges (do not let the mixture boil). Remove from heat.
On your instant-read cooking thermometer, the temperature should reach between 165 and 180 degrees F. This process is known as tempering. NOTE: Do not let the mixture boil or it will curdle. If, of course by accident, your custard base does curdle, immediately remove from heat and place in a blender; process until smooth.
The FDA and the USDA advise consumers to use a recipe that contains a cooked custard base when using eggs in your ice cream recipe. The custard base must reach 160 degrees F, measured with a cooking thermometer, to kill the salmonella bacteria. Additionally, it is important to only used pasteurized milk and cream products in making your homemade ice cream.
Remove the custard mixture from heat and let custard cool. NOTE: Cool quickly by setting pan in ice or cold water and stirring for a few minutes. Using the ice water method, the mixture will cool in about 15 minutes. Once the custard is cool, cover and refrigerate until thoroughly chilled, at least 1 hour or until it reaches 65 degrees F. on your instant-read cooking thermometer.
This is the custard base. This custard base can be used in many other ice cream recipes where you want a rich, creamy ice cream. Place mixture back in the refrigerator for at least 4 hour, but ideally for 24 hours. This aging process will give the mixture better whipping qualities and produce ice cream with more body and a smoother texture.
When the custard base is cold, stir in the heavy cream and vanilla extract or vanilla bean scrapings. Stir or whisk just until mixture is well combined. If you want to add any extra additions (fresh or dried fruit, candies or confections, nuts, or alcohol), now is the time (see below for directions). The ice cream is now ready for the freezing process.
Transfer the mixture into your ice cream maker and freeze according to the manufacturer's instructions. Either churn your ice cream by hand or by motor.
Variation: Add either 1/2 cup or unsweetened cocoa powder or 3 (1-inch) squares unsweetened chocolate or 1/2 cup chocolate syrup to make Chocolate Ice Cream.
* Whole milk, half & half cream, and/or low-fat condensed milk may be used to lower the calories (these substitutions may effect how creamy your ice cream will turn out).
** Rock salt – large crystal salt with a gray color, due to minerals not removed from normal table salt. This form of salt is available in most grocery stores, and also through hardware stores.
Homemade Ice Cream Recipes: https://whatscookingamerica.net/desserts/homemadeicecream.htm