Step 1: In a large, heatproof bowl, vigorously whisk together the egg yolks and granulated sugar until the mixture is pale yellow, thick, and creamy. This should take about 2-3 minutes of consistent whisking. The sugar acts as an abrasive, helping to break down the proteins in the yolks and creating a smoother, more stable base for the custard.
Step 2: In a separate heavy-bottomed saucepan, combine the whole milk, heavy cream, and a pinch of salt. Place the saucepan over medium-low heat, stirring occasionally. Heat the mixture until it is steaming gently and small bubbles begin to form around the edges of the pan, but do not allow it to come to a rolling boil. Scalding the milk helps to enhance its flavor and integrate it seamlessly into your Homemade Eggnog.
Step 3: This is the crucial step of "tempering" the eggs, essential for a perfectly smooth Homemade Eggnog and preventing scrambled eggs. Slowly and gradually ladle about half a cup of the warm dairy mixture into the egg yolk mixture, whisking constantly and vigorously. Continue adding the warm dairy, half a cup at a time, whisking continuously, until about half of the total warm liquid has been incorporated into the eggs. This process slowly raises the temperature of the egg yolks, preventing them from cooking too quickly when returned to the heat.
Step 4: Once tempered, carefully pour the warmed egg mixture back into the saucepan with the remaining warm dairy. Return the saucepan to medium-low heat.
Step 5: Continue to cook the mixture, stirring constantly with a whisk or a heatproof wooden spoon. Cook until the mixture thickens enough to lightly coat the back of a spoon and holds a clear line when you run your finger across it. The ideal temperature is around 175°F (80°C). It is absolutely vital that you do NOT let the mixture boil, as this will almost certainly cause the eggs to curdle and ruin the texture of your Homemade Eggnog. This cooking process usually takes 8-10 minutes. If you have a kitchen thermometer, it’s an invaluable tool here to ensure you reach the correct temperature without overcooking.
Step 6: Immediately remove the saucepan from the heat once the custard has thickened. Pour the custard through a fine-mesh sieve into a clean, large bowl. This step is important to catch any minuscule bits of cooked egg or impurities, ensuring your Homemade Eggnog is perfectly smooth and silky.
Step 7: To cool the custard rapidly and stop the cooking process, place the bowl into a larger bowl filled with ice water (an ice bath). Stir the custard occasionally while it cools down to room temperature. Once cooled, cover the bowl tightly with plastic wrap, pressing it directly onto the surface of the custard to prevent a skin from forming. Refrigerate for at least 4 hours, or preferably overnight. Chilling is essential as it allows the flavors to meld beautifully and ensures a refreshingly cold drink. For optimal storage, especially if making a larger batch, consider transferring your chilled Homemade Eggnog to airtight Basics Glass Food Storage containers before refrigerating.
Step 8: Once thoroughly chilled, it’s time to add your final flavorings. Stir in your desired amount of pure vanilla extract, a generous amount of freshly grated nutmeg, and any desired spirits (dark rum, brandy, or bourbon are traditional and excellent choices). Taste and adjust seasonings to your preference. Remember, adding spirits too early in the cooking process can affect the custard's texture and overall flavor, so it's best to add them after cooling your Homemade Eggnog.