Preheat your oven to 350°F. Grease and flour two 9-inch round cake pans.

In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy. Add eggs one at a time, beating well after each. Stir in vanilla extract.

In another bowl, sift together the all-purpose flour, baking powder, baking soda, and salt. Gradually add to the wet mixture, alternating with milk, mixing until just combined.

Divide the batter evenly between the prepared pans. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean. Cool in pans for 10 minutes before transferring to a wire rack.

In a saucepan, heat sugar over medium heat, stirring constantly until it melts into a thick amber liquid. Add butter, stirring until melted. Slowly pour in heavy cream, whisking continuously. Allow to boil for one minute, then remove from heat and stir in sea salt.

Place one cake layer on a serving plate. Spread caramel frosting on top and drizzle with caramel sauce. Place the second layer on top, repeating the process. Finish with frosting and a caramel drizzle.

Chill the cake before serving to make slicing easier. Serve with coffee or milk for a delightful treat.

Store leftovers in an airtight container at room temperature for up to three days. For longer storage, wrap slices in plastic wrap and freeze for up to two months.