Preheat the oven to 350°F (175°C) and grease and flour three 9-inch round cake pans.

In a medium bowl, whisk together 2 ½ cups of all-purpose flour, 2 ½ teaspoons of baking powder, ½ teaspoon of baking soda, and ½ teaspoon of salt. Set aside.

In a large mixing bowl, cream together 1 cup of softened unsalted butter and 2 cups of granulated sugar until light and fluffy, approximately 3 to 5 minutes.

Add 4 large eggs one at a time, mixing well after each addition, then stir in 1 teaspoon of vanilla extract.

Gradually add in the flour mixture, alternating with 1 cup of buttermilk and ½ cup of cooled strong brewed coffee. Mix until just combined.

Evenly divide the batter among the three prepared pans.

Bake for 25 to 30 minutes, or until a toothpick inserted comes out clean. Cool in pans for 10 minutes before transferring to wire racks.

In a medium saucepan over medium heat, add 1 cup of granulated sugar and stir constantly until melted into a golden amber liquid, about 5 to 7 minutes.

Add 6 tablespoons of butter, stirring until melted, then slowly pour in ½ cup of heavy cream while stirring until smooth. Stir in 1 teaspoon of vanilla extract and a pinch of salt.

In a clean mixing bowl, beat 1 cup of softened unsalted butter for 2 to 3 minutes until creamy.

Gradually add 4 cups of powdered sugar until combined, then mix in ¼ cup of heavy cream, 2 tablespoons of caramel sauce, 1 teaspoon of vanilla extract, and 1 tablespoon of cooled brewed coffee. Beat until smooth.

Layer the cooled cake layers with buttercream frosting between each layer, frost the top and sides generously, and drizzle with cooled caramel sauce before serving.