Preheat oven to 325 degrees Fahrenheit. Grease and flour tube pan and set aside.
Make the Cake Batter: Using a stand mixer fitted with paddle attachment or a hand mixer, cream butter and granulated sugar until it has a pale yellow color (about 3 minutes). Mix in sour cream until incorporated.
½ pound unsalted butter, 3 cups granulated sugar, 1 cup sour cream
In another mixing bowl, sift flour and baking soda together, then stir into the creamed mixture.
½ teaspoon baking soda, 3 cups all-purpose flour
Add the eggs to the mixture, one at a time, fully beating between each addition.
6 eggs
Bake the Cake: Stir the vanilla extract into the cake batter, then pour it into prepared tube pan and bake for 1 hour and 30 minutes or until a toothpick or skewer inserted into multiple parts of the cake comes out clean.
1 teaspoon vanilla extract
Let the cake cool in the pan for 10-15 minutes then carefully invert it onto a plate or wire cooling rack to come to room temperature.
Make the Glaze and Serve: While the cake cools, beat together the powdered sugar, butter, milk, vanilla extract, and salt until smooth and uniform. Pour glaze over top of the cake before serving.
1 ¾ cup powdered sugar, 3 tablespoons unsalted butter, 1-2 tablespoons milk, 1 teaspoon vanilla extract, ½ teaspoon fine sea salt