Cake

1. Preheat oven to 325F/163C and heavily grease and flour a 10-cup bundt pan, set aside while you prepare the filling.
2. In the bowl of an electric stand mixer or large mixing bowl with a handheld electric mixer beat the butter and sugar together for two minutes, scrape down the sides of the bowl then beat again for another 2-3 minutes. This is not a typo, the butter and sugar need to cream for a long time, don't skip this step.
3. While the butter is mixing in a small bowl whisk together the flour, baking soda, baking powder, and salt.
4. Once the butter mixture is light and fluffy add the first egg and mix until no yolk remains. Repeat until all eggs have been added, the mixture may look curdled, which is fine.
5. Add half of the dry ingredients and gently fold in. In a small bowl combine the buttermilk and vanilla extract. Add the buttermilk mixture, mixing until fully combined, but do not over mix.  Add remaining flour mixture. Do not over mix the cake batter, you don't want to over-develop the gluten. 
6. Pour into the prepared cake pan and use an offset spatula to spread the batter into an even layer. Bake for 40-50 minutes, or until a toothpick inserted in the center comes out clean with no wet batter, moist crumbs are okay. The internal temperature of the cake should be 210F/99C.
7. Let the cake cool in the pan for 10 minutes, in this time prepare the sweet butter sauce.

Butter Sauce

1. In a small saucepan combine all sauce ingredients and cook over medium heat for 3-4 minutes. Use a skewer or thin metal piece to poke holes all over the cake. Pour the glaze on top and let the cake sit for 30-45 minutes, no longer or you risk the cake becoming stuck. Place a large plate on top and invert the cake onto a serving platter.
2. Serve with desired toppings and store leftovers in an air-tight container on the counter for up to 4 days.