Step 1

Place 3 sticks of the unsalted butter and 8 ounces cream cheese in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Place 4 large eggs and 1/2 cup sour cream on the counter. Let everything sit at room temperature until the butter and cream cheese are softened, about 1 hour.

Step 2

About 30 minutes before the butter is ready, arrange a rack in the middle of the oven and heat the oven to 325ºF. Place the remaining 1 tablespoon unsalted butter in a small microwave-safe bowl and microwave until melted, 20 to 30 seconds. Add 1 tablespoon of the all-purpose flour and mix to form a smooth paste. Brush the paste on the inside of a 12-cup Bundt cake pan (see Recipe Notes), making sure to thoroughly coat the tube and all the crevices.

Step 3

Place the remaining 3 cups all-purpose flour, 1 teaspoon baking powder, and 1/2 teaspoon kosher salt in a large bowl and whisk to combine.

Step 4

Add 2 2/3 cups granulated sugar to the bowl of butter and cream cheese. Beat on medium speed with the paddle attachment until fluffy and combined, 3 to 4 minutes. Turn the mixer off and add the eggs, sour cream, and 1 tablespoon vanilla extract. Beat on medium speed until thoroughly combined and very light and fluffy, 2 to 3 minutes. Reduce the mixer speed to low, slowly add the flour mixture, and mix until just combined, 1 to 2 minutes.

Step 5

Transfer the batter into the Bundt pan and smooth out the top. Pick up the pan and gently tap on the work surface a few times to remove any air bubbles.

Step 6

Bake until the top is golden-brown and a toothpick inserted in the center comes out clean, 70 to 75 minutes. Place the Bundt pan on a wire rack and let cool 30 minutes. Flip the cake out onto the rack and let cool completely, at least 2 hours, before slicing and serving.