Preheat oven to 350 degrees Farenheit and spray a 12 cup bundt pan with nonstick baking spray.
In a large bowl, sift the cake flour. Whisk in baking soda, baking powder, and kosher salt. Set aside.
3 (375 g) cups Cake flour, ½ teaspoon Baking powder, ½ teaspoon Baking soda, ¾ teaspoon Kosher salt
In a small bowl, combine sour cream and milk and mixed until combined. Set aside.
¾ (180 g ) cup Sour cream, ¼ (60 g) cup Whole milk
In the bowl of a stand mixer, fitted with the paddle attachment, beat butter and sugar on medium low speed until combined, stopping to scrape the sides of the bowl. Increase speed to medium and continue to beat until pale and fluffy, about 4 to 5 minutes.
1 (227 g) cup Unsalted butter, 2 ½ (500 g) cups Granulated sugar
Add eggs, one at a time, beating well after each addition. Add vanilla extract.
4 large Eggs, 1 tablespoon Vanilla extract
With the mixer on low, add flour mixture in three additions alternating with sour cream mixture (in two additions), beginning and ending with the flour mixture. Mix each addition until just combined, scraping down the sides of the bowl as necessary.
Spoon batter into prepared pan and smooth the top with the back of a spoon or offset spatula. Place a kitchen towel on the counter and firmly tap pan on top of the towel to release any air bubbles.
Bake for 50 to 55 minutes until a toothpick inserted into the center comes out clean and the cake springs back to touch. Cool in pan on a wire rack for 10 minutes. Invert cake onto wire rack to cool completely.