Preheat oven to 325°F/165°C.

Add the egg yolks and sugar to a bowl and whisk until smooth. Stir in the eggnog (recipe) until well combined, stir in the bourbon if using.

Place four, 5 ounce ramekins in a shallow baking dish. Pour the brûlée mix into each dish. Pour hot water into the baking dish until it comes halfway up the sides of the ramekins. Bake for 40-45 minutes until the brûlée is set, 

Remove the pan from oven and remove the ramekins using a spatula and allow to cool, then transfer to the refrigerator to chill and set for 3 hours.

Once cooled and set, sprinkle a teaspoon of sugar over each of the brûlée’s and use a culinary blowtorch or broil to brown and crisp the top.