2 Add the milk, 1 cup of the cream, remaining sugar, instant coffee (if using), and the salt to the chocolate base, and whisk vigorously until fully incorporated, then use a rubber spatula to scrape the bottom and sides of the pan. When the chocolate base is smooth, turn heat to medium high, stirring occasionally, wait until the base starts to steam. Whisk the egg yolks in a medium sized bowl. Once the chocolate base has heated to point of being steamy, temper the eggs by slowly pouring some of the hot base into the eggs while whisking the eggs vigorously to prevent them from cooking. Once you've incorporated about half of the base with the eggs, pour the egg mixture back into the pan with the rest of the chocolate base and stir to combine.