Preheat your oven to 350°F.
In a medium bowl, whisk flour, baking powder, and salt together. Set these dry ingredients aside for now.
In an electric mixer, cream the butter, oil, and sugar together until very light and fluffy--around 2-3 minutes. Scrape down the sides of the bowl if needed throughout.
Beat in the eggs, one at a time, followed by the vanilla, until the mixture is smooth. Make sure your eggs are at room temperature before using them.
Fold in half of the dry ingredients, followed by all of the buttermilk, and then the remaining dry ingredients. Gently fold everything together until the flour is just combined.
Use a pastry brush to grease your bundt pan with shortening and a light dusting of flour.
Transfer the batter to your greased bundt cake pan. Bake for 25-30 minutes, or until the cake is set. Once the cake is done, let it rest for 10-15 minutes in the pan before flipping out onto a cooling rack.