Preheat your oven to 325°F. Liberally butter and flour the inside of a 12-cup bundt pan. Put in the freezer for 1 hour, then butter and flour the inside once more.
In the bowl of a stand mixer fitted with the whisk attachment, beat the butter for 1 minute on high speed. Slowly add the granulated sugar. Cream together for an additional 5 minutes, until very pale yellow and fluffy. Add the eggs 1 at a time, combining well after each addition and scraping down the sides and bottom of the bowl as needed.
Turn mixer down to its lowest speed and slowly add flour in 2 batches. Add the salt and baking soda. Add the sour cream, oil and vanilla extract. Scrape down the sides and bottom of the bowl and mix the batter until just combined. Be careful not to overmix. Set the batter aside.
For the Cinnamon Swirl, in a small bowl, whisk together all the ingredients until well combined. Set aside.
Pour 1/3 of the batter into the prepared pan. Drizzle 1/2 of the cinnamon swirl over the batter. Using a butter knife or skewer, swirl the mixture through the cake batter.
Repeat with the rest of the cake batter and cinnamon swirl. Top with the remaining batter. Bake for an hour and a half to an hour and 45 minutes, or until a toothpick inserted into the center of the cake comes out mostly clean.
Let the cake cool in the pan on a wire rack for 10 minutes, then invert onto a serving plate. Let cool to room temperature. Lightly cover the cake with foil or plastic wrap so it does not dry out.
For the Icing, clean your stand mixer bowl and whisk attachment. Beat the cream cheese and butter for 2 minutes on medium-high speed. Reduce your mixer speed and carefully add the confectioners’ sugar in 2 batches, scraping down the sides and bottom of the bowl as needed. Once the sugar is fully incorporated, turn your mixer back up to medium-high speed and add the milk and vanilla extract. Beat until the icing is smooth and pourable.
Drizzle the icing over the cooled pound cake. Serve at room temperature.