Preheat the oven to 325ºF.

Generously grease the inside of a 10-inch bundt pan with butter or shortening and dust it with flour. Tap out any excess flour.

Combine the butter and sugar in a large bowl and cream until light and fluffy. Add the eggs, one at a time, beating well after each addition. Beat in the vanilla.

In another bowl, whisk the flour, baking powder, salt and baking soda together.

Mix 1/3 of the flour mixture into the butter and sugar mixture. Add half of the buttermilk and mix to combine, followed by another 1/3 of the flour mixture. Finish by beating in the remaining buttermilk, and finally the last of the flour. Use a spatula to make sure the mixture is completely mixed in. The batter will be thick.

Pour the batter into the prepared bundt pan.  Bake until a tester inserted in the center comes out clean, about 60 minutes.

Let the cake cool for 15 minutes, then remove from the pan to cool completely on a wire rack.

Once the cake is cool, place it on a serving plate.

Place the butter, brown sugar and cream in a saucepan and place over medium heat. Bring the mixture to a boil, stirring constantly. Remove from the heat. Whisk in the powdered sugar.  Let the icing sit for 10-15 minutes, whisk one more time, then pour the icing over the cake. Let the icing set before serving.