1. Preheat oven to 325 F. Butter and lightly flour a 10-12 cup bundt pan. Tap out excess flour. Refrigerate pan until ready for use.
2. Beat butter in the bowl of a stand mixer until very light, about a minute or two. Scrape the sides of the bowl with a silicone spatula and add oil and beat until smooth and combined. Add sugar and beat until fluffy and pale, about 3 minutes.
3. Add eggs, 1 at a time, mixing just until combined.
4. In a separate bowl, whisk together flour, baking powder and salt. Mix vanilla into buttermilk.
5. Alternate additions of the flour and buttermilk mixtures to the butter, beginning and ending with flour. Scrape the bowl after each addition. Do not over-mix.
6. Pour batter into prepared pan, leaving at least an inch from the top of the pan. Tap the pan on the counter several times to smooth out the batter and remove any air bubbles.
7. Bake for about 60 minutes, give or take 5 minutes, or until a toothpick or cake tester comes out clean from the center of the cake.
8. Cool for 30 minutes on a wire rack before turning out of pan. Turn out onto the rack and cool completely before glazing.

Glaze

1. Click the link above for the recipe.