Place the batter in a preheated 10 oz Irish Coffee mug.
Add the rum and cognac.
Heat the milk with a hot pot (or in a saucepan).
Briskly stir the batter with a short whisk or spoon while adding the heated milk so that the ingredients are beaten together.
Top with freshly grated nutmeg.
*Tom & Jerry batter: Separate yolks and whites of 12 eggs. Run egg whites through a food processor until stiff. Transfer to a bowl. Run egg yolks until through a food processor until they are thin as water. While the food processor is running, add 2 lbs white sugar, 1 tsp ground cinnamon, 1/2 tsp ground allspice, 1/2 tsp ground nutmeg, 1/2 tsp ground cloves, 2 oz añejo rum (like Plantation Barbados), 6 tbsp fine Madagascar vanilla extract and 4 dashes Angostura bitters to egg yolks. Add egg whites back into egg yolk mixture and whisk together. Store inside a sterilized container in refrigerator.