Arrange a rack in the middle of the oven and heat to 375ºF. Coat a 10-inch aluminum tube pan or 2 (9-by-5-inch) loaf pans with 1 tablespoon of butter and dust with 2 tablespoons of the flour.
Combine the remaining 12 ounces of butter and the sugar in the bowl of a stand mixer fitted with the paddle attachment and cream for 6 minutes on medium speed. Stop once to scrape down the sides of the bowl with a spatula. Turn the mixer down to its lowest speed and add the eggs, 1 at a time, making sure each egg is fully incorporated before adding the next. Again, stopping once to scrape down the sides of the bowl. This will take approximately 1 1/2 minutes. Add the vanilla and salt and beat on medium speed for 30 seconds.
With the mixer on the lowest speed, add the flour in 3 installments, alternating with the buttermilk, beginning and ending with the flour, and making sure each portion is fully incorporated before adding the next. After the final addition, beat the batter for 30 seconds on medium speed until almost smooth.
Scoop the batter into the prepared pan(s), dividing evenly if using 2 pans. Bake until the internal temperature reaches 210ºF on an instant-read thermometer, about 1 hour. The crust will be golden brown and spring back when pressed, but the crack around the center will appear moist.
Remove the cake from the oven to a wire rack for 10 minutes. Remove the cake from the pan(s) and cool completely on the rack. Store the cake on the rack covered with a tea towel for up to 3 days.