Preheat your oven to 315 degrees and prepare your 12 cup bundt pan with shortening and flour or non-stick baking spray.
In your mixer bowl, cream together butter, granulated sugar and salt on high speed until light and fluffy for 5 minutes.
Next add in eggs, one at a time, and mix until well incorporated.
Slow mixer to lowest speed and carefully add in flour then eggnog, vanilla extract and nutmeg and mix until just combined.
Pour cake batter into bundt pan and bake for 65-75 minutes or until a toothpick inserted into the center comes out moist but mostly clean.
Cool cake for 10 minutes then invert cake onto cooling rack.
For the Butter Rum Sauce:
Add butter, water, sugar and rum into a pot and bring to a boil and allow to combine. Poke cake all over its surface then pour sauce over the cake allowing it to seep into the cake. Once completely soaked in then sprinkle with powdered sugar and serve.
Poke small holes on the surface of the cake all over then pour butter rum sauce over the cake allowing it to seep into it.