Preheat the oven to 350° F. Grease and flour a 10-inch bundt pan.
In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
3 cups all-purpose flour, 1/2 teaspoon baking powder, 1/2 teaspoon salt
In a large mixing bowl, beat the softened butter and shortening with an electric mixer until smooth and creamy.
1 cup unsalted butter, 1/2 cup vegetable shortening
Gradually add the sugar, beating until the mixture is light and fluffy.
3 cups granulated sugar
Add the eggs one at a time, beating well after each addition.
5 large eggs
Add the flour mixture to the butter mixture in three additions, alternating with the milk.
1 cup milk
Begin and end with the flour mixture, mixing just until combined after each addition.
Mix in the vanilla extract.
1 teaspoon vanilla extract
Pour the batter into the prepared bundt pan and spread it into an even layer.
Bake for 1 hour to 1 hour and 30 minutes, or until a toothpick inserted near the center of the cake comes out clean.
Let the cake cool in the pan for 15 minutes. Carefully remove it from the pan and transfer it to a wire rack to cool completely.