Preheat the oven to 350 F and place the dry ingredients in a bowl. Using a whisk, mix them.
Using a hand-held or stand mixer, cream the butter and sugar in a large bowl until smooth. Add the eggs, sour cream, and vanilla extract. Beat just until combined.
Alternating, add the dry ingredients and milk in a few additions to the egg mixture.
Pour the batter into a greased 9x13-inch baking dish.
Making the cinnamon swirl:
In a medium-sized bowl, mix the softened butter, brown sugar, flour, cinnamon, and salt.
Add spoonfuls of this mixture into the cake batter and using a fork, swirl them into the cake batter. Bake for 40 mins or until a toothpick inserted into the middle comes out clean.
Making the glaze:
Using a hand mixer, beat the cream cheese, vanilla, milk, and powdered sugar together until smooth.
Spread over the warm cake and enjoy!
Notes
Make sure the butter, eggs, and cream cheese are all softened and room temperature to ensure the proper mixing of the batter, cinnamon swirl, and glaze.
Every oven is different, so don’t rely on the cooking time. It’s better to always do the toothpick method!