In a mixing bowl, you will add 2 sticks of softened unsalted butter and then add 1/2 cup of shortening be sure to mix them together.
Once you've mixed the butter and shortening, you will begin to add in 3 cups of granulated sugar a little at a time while still mixing.
As you're mixing you will begin to add your 5 eggs to mix 1 egg at a time and be sure to continue mixing after each egg is added. It's important to add your eggs this way so they can mix in evenly and it also allows for your batter to thicken naturally.
Now in a separate bowl, you will begin to add 3 cups of all-purpose flour, 1/2 teaspoon of salt, and 1/2 teaspoon of baking powder, which are your dry ingredients.
Stir these ingredients with a large spoon, and then add to your cake batter. Start adding some flour, a little at time, add your milk. Then begin to alternatively add your milk, flour, milk, and flour. Don’t forget to add your 1 teaspoon of vanilla flavor to your cake mixture.
Preheat your oven to 350 degrees, and when your cake is well mixed, pour into a greased and floured bundt pan. Your cake will cook for about 1 hour and 10 minutes, or until your toothpick comes out clean.