Preheat your oven to 350°F (175°C). This ensures your cake bakes evenly.
Grease and flour your 9-inch round cake pans. This helps the cake release easily once baked.
In a bowl, whisk together 3 cups of all-purpose flour, 2 teaspoons of baking powder, 1 teaspoon of baking soda, and a pinch of kosher salt. Set aside.
In a large mixing bowl, beat 1 cup of softened butter and 2 cups of sugar together until light and fluffy, about 3-4 minutes.
Add 4 room-temperature eggs, one at a time, mixing well after each addition. Then, blend in 2 teaspoons of vanilla extract.
Gradually add the dry ingredient mixture to the butter mixture, alternating with 1 cup of room-temperature buttermilk. Start and end with the flour mixture, mixing until just combined.
Divide the batter evenly between the prepared cake pans, smoothing the tops with a spatula.
Bake in the preheated oven for 25-30 minutes or until a toothpick inserted into the center comes out clean.
Once baked, remove the cakes from the oven and let them cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.
In a mixing bowl, combine 1/2 cup of shortening and 1/2 cup of softened butter. Beat until creamy. Gradually add 2 cups of confectioners sugar and mix well. Stir in 1/2 teaspoon of sea salt and adjust to taste.
Once the cakes are completely cool, place one layer on a serving plate. Spread a generous amount of salted caramel buttercream on top, then place the second layer on top and frost the top and sides of the cake.
Slice your beautiful butter cake and serve it with a drizzle of additional salted caramel sauce if desired. Enjoy every bite of this indulgent treat!
