1. Preheat oven to 325°F. Butter and lightly flour a 10–12 cup bundt pan. Tap out excess flour. Refrigerate the pan until ready to use.
2. Beat the butter in the bowl of a stand mixer until very light, about 1–2 minutes. Scrape down the bowl, add the oil, and beat until smooth and combined. Add the sugar and beat until fluffy and pale, about 3 minutes.
3. Add the eggs one at a time, mixing just until combined after each.
4. In a separate bowl, whisk together the flour, baking powder, and salt. Stir the vanilla into the buttermilk.
5. Add the flour and buttermilk mixtures to the butter alternately, beginning and ending with the flour. Scrape the bowl after each addition. Do not overmix.
6. Pour the batter into the prepared pan, leaving at least an inch of space from the top. Tap the pan on the counter several times to settle the batter and release any air bubbles.
7. Bake for about 60 minutes (±5 minutes), until a toothpick inserted in the center comes out clean.
8. Cool on a wire rack for 30 minutes before turning out. Invert onto the rack and cool completely before glazing.

Vanilla Glaze

1. In a medium bowl, whisk together the sifted confectioners’ sugar, 3 tablespoons of milk, vanilla extract, and salt until smooth. Add the remaining tablespoon of milk if needed to reach a slowly dripping, pourable consistency.
2. Pour the glaze slowly over the top of the cooled bundt, letting it drip naturally down the sides. Allow to set for 10–15 minutes before slicing.