Preheat your oven to 350°F (175°C). Grease and line two 9-inch round cake pans with parchment paper.

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

In a large mixing bowl, cream the butter and sugar until light and fluffy, about 2–3 minutes.

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

Gradually add the dry ingredients to the butter mixture in three additions, alternating with the buttermilk and dissolved coffee. Mix until just combined.

Divide the batter evenly between the prepared pans and bake for 25–30 minutes, or until a toothpick inserted into the center comes out clean.

Let the cakes cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

In a medium saucepan, combine the granulated sugar and water over medium heat. Cook without stirring until the sugar dissolves and turns a deep amber color, about 8–10 minutes.

Carefully whisk in the heavy cream (the mixture will bubble up). Add the butter and salt, stirring until smooth. Let the caramel cool to room temperature before using.

In a large bowl, beat the softened butter for the frosting until creamy. Gradually add the powdered sugar, one cup at a time.

Add the dissolved coffee, vanilla extract, and salt to the frosting. Beat until the frosting is smooth and fluffy.

Place one cake layer on a serving plate. Spread a thin layer of caramel filling over the top. Add a layer of buttercream frosting on top of the caramel.

Place the second cake layer on top and frost the entire cake with the coffee buttercream. Drizzle caramel sauce over the top and garnish with coffee beans or chocolate shavings if desired.

Slice and serve.