Grease and flour a 10-inch bundt pan and set aside.
In a large bowl using a hand mixer or a stand mixer with a paddle attachment, cream the butter and the cream cheese together until very smooth and creamy, making sure to scrape the sides of the bowl to remove any cream cheese lumps! Take your time and make sure this is smooth and creamy!
Add in the white sugar very gradually and beat until fluffy and combined completely. Have patience during this part and make sure it's combined well with no lumps!
Beat in the eggs one at a time, beating very well with each addition, then add in the vanilla.
Whisk together the flour and the cornstarch. Mix into the wet ingredients completely.
Pour the batter into your prepared pan. Run a knife through the batter a few times to remove any large air bubbles.
Place in a COLD OVEN on the middle rack and close the door. Turn the oven to 325 °F and bake for 80-85 minutes, checking for doneness around the 60 minute mark by inserting a toothpick into the center of cake and by the inner tube area. When the cake is done, the toothpick will come out clean. This can take a long while have patience and keep testing!
Let cool in the pan for 5 minutes, then turn out onto a baking rack to cool completely. Dust with powdered sugar, or glaze with icing and serve.
You will notice that you have to have patience for many steps in this! Pound cakes are a lower and slower bake, and take time!