The Tom & Jerry is a Christmas cocktail that became prominent in the United States after bartender Jerry Thomas published the recipe in his 1862 book The Bartender's Guide: How to Mix Drinks. Now relatively unknown except for in the Midwest where it continues to be a Christmastime staple, it's essentially a spiked version of eggnog that mixes a thick egg-based batter with a split base of spiced rum and brandy, milk, and nutmeg.
Add milk, rum, and brandy to a saucepan.
Cook over medium heat for 5-10 minutes while stirring with a spoon until mixture is warmed through.
Using a measuring cup, scoop 2 TBSP batter into mugs.
Top batter with 3-4 oz warm mixture.
Using a bar spoon, stir for 3-5 seconds.
Garnish with grated nutmeg.