Preheat oven to 350. Butter and flour a standard Bundt pan. Set aside.
In a large bowl or bowl of a stand mixer, cream together the butter and sugar until fluffy. Add the buttermilk, eggs, vanilla and soup and beat until smooth.
In medium bowl, whisk together the dry ingredients and stream them into the soup mixture while the beater is running until a thick, glossy batter forms. Scrape into prepared pan.
Bake 45 minutes or until a toothpick or thin knife inserted towards the center of the cake come back virtually dry.
Cool on wire rack in the pan for 10 minutes, unmold and cool completely on wire rack.
Notes
Add a simple glaze--whisk together 1/2 cup of buttermilk, 1/2 cup confectioners sugar and 1 tablespoon cocoa and drizzle it over the cooled cake.