Begin by separating egg yolks from egg whites. Save the egg whites to use in another recipe. Put egg yolks in a bowl, and add in brown sugar and molasses. Add in spices, salt, and whisk till creamy. Set aside.

In a medium saucepan, warm up the milk and heavy cream until steamy. Be sure to stir with a wooden spoon or whisk while heating to avoid the milk burning on bottom of the pan.

Now it is time to temper the eggs. Once the milk mixture is warm, using a cup or ladle, measure half of it into the egg mixture, constantly stirring. It is now time to add the egg mixture back into the remaining warm milk mixture.

Continue to cook until mixture thickens slightly, and coats the back of a spoon. Using a candy thermometer, cook until temperature registers 160 F. Remove from heat,  add vanilla, and cool. If weather is cool outside, allow to cool covered on the back porch. Then finish cooling in the fridge.

At this point, you can keep the mixture as is in a mason jar, or mix with additional milk if serving as eggnog with no alcohol. If you plan to use to make boozy eggnog, simply add rum, or bourbon, and a bit of milk as needed.