For the cake: Preheat oven to 350 degrees F. Spray three 8-inch round cake pans with nonstick baking spray and set aside.
Combine the sugar and butter in a large mixing bowl; cream together until light and fluffy, using an electric mixer on medium to high speed, about 2 minutes. One at a time, add the eggs, making sure to mix well between each addition. Split the vanilla beans in half lengthwise and scrape out the seeds with a knife; add to the batter and mix until well incorporated.
In a separate mixing bowl, sift together the baking powder, baking soda, salt and flour. Pour half of the flour mixture into the batter and mix on low to medium speed until well incorporated, scraping the bowl as needed. Add the buttermilk to the batter and continue mixing until well incorporated. Add the remaining flour mixture; mix until all ingredients are well combined. Pour the batter into the prepared cake pans, making sure it is evenly distributed. Bake until a knife inserted into the middle of the cake comes out clean, about 45 minutes. Allow the cakes to cool completely before stacking.
For the salted caramel filling: Add the sugar to a saucepan and cook on low to medium heat until fully melted and beginning to acquire a caramel color, about 10 minutes. Add the butter and mix until blended. Once the butter is incorporated into the sugar, cook for another 2 minutes over low heat, being sure not to burn the mixture. Add the heavy cream, then turn off the heat and let the mixture bubble, stirring just once. When the bubbling stops, add the sea salt. Let cool.
For the buttercream frosting: Combine the butter, shortening and cream cheese in a large mixing bowl; blend with an electric mixer on medium speed until light and fluffy. Add the vanilla extract, then blend in the powdered sugar, one cup at a time, until incorporated. Once all the sugar is incorporated, blend for 1 minute more, or until frosting is smooth.
Spread the salted caramel filling between the cake layers and then stack the cake. Frost with the buttercream frosting.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.