Preheat the oven to 350°F (175°C) and grease two 9-inch round cake pans with butter or cooking spray.

In a large mixing bowl, beat the softened butter and brown sugar until light and fluffy, about 3-4 minutes.

Incorporate the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.

Alternately add the dry ingredients and buttermilk to the wet mixture, starting and ending with the dry ingredients. Mix until just combined.

Divide the batter evenly between the prepared pans and bake for approximately 30 minutes, or until a toothpick inserted into the center comes out clean.

Let the cakes cool in the pans for 10 minutes before transferring to wire racks to cool completely.

In a saucepan over medium heat, combine the brown sugar and butter, stirring until melted.

Add the heavy cream and bring to a boil. Allow the mixture to boil for 2-3 minutes before removing from heat.

Stir in the vanilla and salt while allowing it to cool slightly.

Once the cakes are completely cooled, drizzle caramel icing over the top of the first layer, then place the second layer on top. Finish by drizzling more icing over the top.