Preheat oven to 350. Spray a loaf pan with vegetable spray and set aside. Combine flour, instant pudding, baking powder, salt and nutmeg in a medium bowl and set aside. Add butter to a large bowl and cream. Add in the sugar and mix with a hand mixer until light and fluffy. Add in the eggs, one a time, mixing in between. Add in the eggnog, vanilla and rum extract, if using and mix well. Finally, fold the cranberries. Spread evenly into the prepared loaf pan and bake for 1 hour and 15 minutes or until a toothpick inserted into the cake comes out clean. Baking times may vary so after about an hour, I start to watch it a little more closely to ensure that it's not overcooked. Remove from oven, let cool for 10-15 minutes and then remove from the loaf pan to a cooling rack and continue to let cool.