• Preheat oven to 350º F and prepare a 12 inch cast iron skillet with oil or cooking spray, sprinkle with 2 tablespoons coarse sugar if desired.

Butter Cake Batter

• In a large mixing bowl or stand mixer cream together the 1 cup butter and 4 ounces cream cheese. Add in the 1 3/4 cup sugar, 4 eggs and 1 1/2 teaspoons vanilla. Continue mixing until fluffy, scrapping down the sides if needed.
• Add in the 2 cups flour and 1/2 teaspoon coarse sea salt, continue mixing until combined.
• Spread the cake batter evenly into the prepared skillet.

Cream Cheese Layer

• In a separate mixing bowl cream together the 4 ounces cream cheese, 1/2 cup sugar, 1 egg yolk and 1/2 teaspoon vanilla. Mix with the electric mixer until well combined.
• Drop the cream cheese mixture over the top of the cake batter in the skillet, then spread evenly over the cake batter.
• Bake the cake for 40-45 minutes until a toothpick comes out with just a few crumbs when inserted into the center of the cake.
• Cool for 15-20 minutes before slicing.