In a medium mixing bowl, vigorously whisk together the eggs and granulated sugar until the mixture turns creamy and lightens in color, around 2-3 minutes.
In a medium saucepan, combine the whole milk, heavy whipping cream, and amaretto syrup. Place the saucepan over medium heat and warm the mixture until it starts steaming but do not allow it to boil.
Gradually pour the hot milk mixture into the egg-sugar mixture while continuously whisking to ensure the eggs do not scramble (this process is known as tempering).
Once fully integrated, return the combined mixture back to the saucepan. Cook over low heat for approximately 5-7 minutes, stirring constantly until the mixture thickens enough to coat the back of a wooden spoon.
Remove the saucepan from the heat and mix in the pure vanilla extract, freshly grated nutmeg, and ground cinnamon until evenly combined.
Allow the creamy mixture to cool at room temperature for about an hour, then transfer it to the refrigerator to chill for at least two hours, or until thoroughly chilled.
Before serving, give the eggnog a good stir to recombine any settled ingredients and carefully pour it into glasses or festive mugs.
Crown each serving with a generous dollop of whipped cream and finish with a playful maraschino cherry on top.
Notes
Serve in clear glasses to showcase the creamy texture, and consider using festive straws or sprinkles for an extra touch of whimsy!