Preheat your oven to 350F (175C) and butter and flour a loaf pan. You may also want to line the bottom with parchment paper for extra insurance.
In a large mixing bowl, cream together the butter and the sugar by beating them with an electric mixer on medium high for about five minutes. You want the mixture to be pale and fluffy.
Turn your mixer down a notch and beat in the eggs one at a time until combined.
In a separate bowl, sift together the flour, baking soda, baking powder, and salt. Also measure out your buttermilk in another container or measuring cup, and add the vanilla extract to it. If you have a stand mixer, you can do this while your butter and sugar are being creamed.
With your mixer on it's lowest setting, tip in a third of your dry ingredients, followed by half of your buttermilk, beating each time until everything is just combined. Keep going with another third of the dry stuff, the rest of the buttermilk, and then the last of the dry ingredients until everything comes together.
Ditch the electric mixer, being sure to scrape off as much of the batter as you can. Give the bowl one last scrape and gentle mix with a rubber spatula, and then transfer your thick batter to your waiting loaf pan. Smooth out the top, and bake for 40-45 minutes or until it's golden on the top and a cake tester comes out clean.
Allow your cake to cool in the pan for about ten minutes, then gently turn it out of the pan and allow it to continue to cool on a wire rack.
Slice and serve with your favorite accompaniments.