Grease & flour (or line with parchment paper) a 9 x 6 x 3 inch (or 23 x 12 x 6cm) loaf tin.
In a large bowl, combine sugar, beaten eggs, eggnog, rum/ rum flavoring, vanilla extract, and softened butter.
Sift flour, baking powder, salt, nutmeg, and cinnamon into the eggnog mixture.
Stir util just combined. (Do not over-stir!)
Scoop dough into prepared greased (or papered) loaf tin.
Bake in preheated oven for 50 minutes.
Remove from oven and check for doneness with skewer.
If cooked, allow eggnog bread to cool in the loaf tin for 10 minutes, then turn out onto a cooling rack. Allow to cool completely on cooling rack before cutting into thick slices.
Notes
You can use store-bought eggnog, or you can use one of my homemade eggnog recipes.