Preheat oven to 325°. Generously coat 12-cup Bundt pan with room-temperature unsalted butter, making sure to get into crevices, then dust with all-purpose flour, tapping out any excess.

Beat 1 cup (2 sticks) unsalted butter, room temperature, and one 8-oz. package cream cheese, room temperature, in a large bowl with an electric mixer (either a stand mixer fitted with the paddle attachment or a hand mixer with beaters) on medium speed until light and fluffy (about 4 minutes if using a stand mixer; 6–8 minutes if using a hand mixer).

Scrape down sides of bowl. Add 3 cups sugar and 1 tsp. Diamond Crystal kosher salt or ½ tsp. Morton kosher salt and beat 5 minutes.

Scrape down sides of bowl, then, with the motor running, add 6 large eggs, room temperature, one at a time, beating after each addition until incorporated before adding more.

Add 4 tsp. vanilla extract and beat just until combined (mixture will look grainy and broken).

Reduce mixer to low speed. Add 3 cups sifted all-purpose flour and beat until smooth (be careful not to overbeat).

Scrape pound cake batter into prepared pan.

Bake cake until a toothpick or other tester inserted into the center comes out clean, 70–75 minutes.

Transfer pan to a wire rack and let cake cool in pan 15 minutes.

Turn cake out onto rack, loosening with a small offset spatula if needed, and let cool completely.