Preheat oven to 350°F and generously grease and flour a 10-inch bundt pan. Shake out excess flour and set aside.
Place 2 cups unsalted butter (softened) in a stand mixer. Beat until creamy and smooth.
Scrape down the sides of the bowl and add 3 1/2 cups granulated sugar. Beat until light and fluffy, about 2 minutes.
In a separate bowl, combine 6 large whole eggs, 6 large egg yolks, 1 tablespoon vanilla extract, and 1 teaspoon salt. Lightly whisk with a fork until combined.
With the mixer on low speed, slowly pour the egg mixture into the butter mixture until fully incorporated.
Scrape down the bowl, then increase speed to medium-high and beat for 1–2 minutes.
Reduce speed to low and gradually add 3 1/2 cups all-purpose flour, about 1/2 cup at a time, until fully mixed.
Scrape the bowl again and mix on medium speed for 1 more minute until smooth.
Spread batter evenly into prepared bundt pan and smooth the top with a spatula.
Bake for 60–75 minutes, or until a toothpick inserted in the center comes out clean.
Allow cake to cool for at least 20 minutes, then run a knife around edges and center.
Carefully invert onto a cooling rack and let cool completely before slicing and serving.