Preheat the oven to 325 degrees F. Use a basting brush to coat a tube or Bundt cake pan with shortening. Dust it with flour. Shake out any extra flour once the pan is coated.
Sift 3 cups flour into a large mixing bowl. Whisk in the baking powder and salt until blended well. Set aside.
With a mixer, beat the butter and shortening together until light and fluffy.
Add the sugar a cup at a time and beat until well mixed.
Add the eggs one at a time, beating just until incorporated.
Mix the vanilla, milk, and sour cream in a small bowl.
Add the flour mixture slowly, alternating with the sour cream mixture. Continue alternating the dry and wet ingredients, beginning and ending with flour. Do not overbeat the batter.
Pour the batter into the prepared pan.
Bake for 1 hour and 30 minutes or until an inserted toothpick comes out clean or with crumbs. Do not overbake.
Cool in the pan for 10 minutes and then turn out onto a cake plate or cooling rack.
Glaze
Beat the cream cheese until smooth. Add the whipping cream, vanilla, and salt. Beat well.
Add the sugar, by 1/2 cupfuls, and beat until smooth. Drizzle on top of the cake.
Notes
Room Temperature Ingredients
Refrigerated ingredients such as butter, sour cream, and eggs must be at room temperature. Take them out of the refrigerator 2 hours before starting the cake.
Sour Cream
For best results, use full-fat sour cream.
Use Aluminum Foil
Check the cake 15-20 minutes before it has finished cooking. If it looks like it might get too brown, place a sheet of aluminum foil (sprayed with cooking spray) on the top of the cake to prevent overbrowning.
Light Colored Pan
This cake cooks best in a light-colored cake tube pan. If you use a dark-colored pan, the cake can overcook so consider lowering the temperature by 25 degrees.