Preheat oven to 325°F (163°C) and grease a 10-inch Bundt pan.
Mix dry ingredients – In a bowl, whisk together flour, salt, baking powder, and baking soda.
Cream butter and sugar – Beat butter, sugar, and oil until light and fluffy. Add eggs one at a time, mixing well.
Add wet and dry ingredients – Alternately mix in buttermilk and dry ingredients, then stir in vanilla.
Bake – Pour batter into the pan and bake for 1 hour 10 minutes or until a toothpick comes out clean.
Cool the cake – Let it rest in the pan for 10 minutes, then transfer to a wire rack.
Prepare glaze – Heat butter, brown sugar, vanilla, and buttermilk in a saucepan. Whisk in sifted confectioner’s sugar until smooth.
Glaze and serve – Drizzle over the cooled cake and enjoy!