Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt.

Add buttermilk, oil, eggs, and vanilla extract. Beat until well combined.

Stir in hot coffee until batter is smooth.

Pour batter evenly into prepared pans and bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.

Let cakes cool in pans for 10 minutes before inverting onto a wire rack to cool completely.

In a large bowl, beat butter until creamy. Gradually add powdered sugar, beating until light and fluffy.

Stir in caramel sauce and sea salt until well combined.

Place one cake layer on a serving plate. Spread with a generous layer of salted caramel frosting. Top with the second cake layer.

Frost the top and sides of the cake with the remaining frosting.

Drizzle with additional caramel sauce and sprinkle with sea salt, if desired.