In a bowl, whisk together egg yolks and sugar until creamy.

In a saucepan over medium heat, add milk, cream, cinnamon sticks and vanilla. Warm until it starts to steam (around 55ºC) - don't allow to simmer or boil.

Add around a cup of milk slowly into the yolks and whisk to temper. Pour the whole mixture back into the saucepan.

Cook the eggnog on a medium to low heat until is slightly thickened (I cooked until about 70ºC). It is ready when it coats the back of a spoon.

Strain into a jug and place into the fridge to cool completely. Then stir in your rum and bourbon.

To serve, divide among cups and top with freshly grated nutmeg.