To Make the Cinnamon Cream Cheese Filling:

1. Add room-temperature cream cheese to a large mixing bowl.  Mix with a hand mixer or stand mixer until the cream cheese is completely smooth.
2. Add the egg, brown sugar, cinnamon, pure vanilla extract, and fine sea salt and blend until smooth.
3. Set aside.

To Make the Batter:

1. Set your oven to a true 325°F.  An oven thermometer is extremely useful here, since most ovens will not reach 325°F when set to 325°F.  
2. Sift together the all-purpose flour, kosher salt, and baking soda in a medium bowl.  Set aside.
3. Add the room-temperature butter and cream cheese to the bowl of your stand mixer or a large mixing bowl.  Mix with your hand or stand mixer until the butter is completely smooth.  Add the granulated sugar and cream until the mixture is light and fluffy.
4. Add the eggs, one at a time, mixing each egg until it is completely incorporated into the mixture.  Scrape the sides and bowl as needed to ensure even mixing.
5. Add the vanilla and mix thoroughly.
6. Add half of the flour mixture and mix until just combined.
7. Add all of the sour cream and mix until just combined.
8. Add the second half of the flour mixture and mix until just combined.  Using a rubber spatula, give the sides and bottom of the bowl a final scrape to ensure that the batter is evenly mixed.
9. Prep a 10- or 12-cup bundt pan as you normally would (I use butter and flour to prep pans for this cake)
10. Add 1/2 of the batter to the pan.  Gently tap to get out any air bubbles. 
11. Add the cream cheese mixture (all of it) to the top of the batter, making sure to avoid the sides!
12. Add the second half of the batter to the bundt pan.  Use a rubber spatula to even out the batter, then *very gently* tap the pan on the countertop several times to remove air bubbles from the batter.
13. Bake for 60-70 minutes in a true 325°F oven, or until an instant-read thermometer reads 212°F-215°F.  

To Make the Cinnamon Simple Syrup:

1. Add sugar, cinnamon, salt, and water to a small saucepan.  Bring to a boil and reduce to a simmer.  Remove from the heat as soon as the sugar is completely dissolved.
2. Add pure vanilla extract and stir to combine.
3. Allow the cake to cool in its pan for ten minutes, then invert and place on top of a cooling rack.  Brush simple syrup on the cake and allow to cool completely.

To Make the Cream Cheese Glaze:

1. Add the room-temperature cream cheese to a large mixing bowl or the bowl of a stand mixer.  Mix until completely smooth.
2. Add the confectioner’s sugar, whole milk, and vanilla extract to the bowl.  Mix on low speed until there are no more lumps.
3. Use a spouted measuring cup, spoon, or squeeze bottle to add the glaze to the completely cooled cake.
4. Enjoy!