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Most types of ice cream machines have a bowl that needs to be frozen for several hours. If you forgot or didn't get a chance to freeze the bowl, prepare the base as instructed in the following steps. Put the base into the fridge and the bowl in the freezer, then churn it the following day. French-style ice cream is also called custard style. It is made with egg yolks, which gives the ice cream a smooth, rich, and creamy taste and texture. Place a large bowl into a sink. Fill the sink with enough ice and cold water to reach to of the way up the side of the bowl. Place a strainer over the bowl. The ice bath should be more "ice" than "water." You will be tempering the eggs to reduce curdling, but some curdles may form. The strainer will catch them. Separate the yolks from the whites first. Place the yolks into a medium-sized mixing bowl and add the sugar. Whisk the two together until the mixture turns pale yellow. Set the bowl aside when you are done. The mixture will be thick and dark yellow at first; keep whisking until it turns pale. Pour the milk into a medium-sized saucepan, then place it on the stove. Add the vanilla extract, then bring the milk to a simmer over medium heat. Once it comes to a simmer, remove it from heat. You can also use a vanilla bean pod instead. Split the bean in half, then scrape the seeds into the milk. Add in the pod as well. Consider adding other herbs and spices to the milk for extra flavor, such as mint leaves, lavender flowers, coffee beans, chocolate, etc. Measure out to 1 cup (120 to 240 milliliters) of the hot milk. Slowly pour it into the egg mixture, whisking while you do so. This will help gradually warm up the egg mixture and prevent it from curdling in the next step. Stir the tempered egg mixture into the milk first. Place the saucepan back on the stove and turn the heat up to low. Stir the custard base slowly, but constantly, as it cooks. Be sure to scrape the bottom and sides of the saucepan often. You are ready for the next step when the custard turns thick enough to coat the back of a spoon and reaches 170F (77C). Once you have everything in the bowl, lift the strainer out. If you see anything caught in the strainer, such as egg curdles or vanilla bean pods, throw them out. You can leave the custard base in the ice bath for 20 minutes, stirring it occasionally. You can also cover the bowl with plastic wrap, then refrigerate it for 3 to 8 hours. For extra flavor, stir in your favorite extract, liqueur, or flavoring oil.
Place the ice cream bowl into the freezer the night before. Set up an ice bath on the day you're ready to make ice cream. Whisk the egg yolks and sugar. Heat the milk, then add the vanilla. Temper the egg mixture with the hot milk. Pour the egg mixture into the milk, then heat it until it thickens. Pour the custard base through the strainer into the ice bath bowl. Stir the heavy cream into the custard, then chill it completely.