Preheat and Prepare Pans: Preheat your oven to 350°F (175°C). Grease and line three 8-inch round cake pans.

Batter Preparation: In a large bowl, cream together the butter and granulated sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract. In another bowl, combine the flour, baking powder, and salt. Gradually add the dry ingredients to the butter mixture, alternating with the brewed coffee. Begin and end with the flour mixture. Mix until just combined.

Bake the Cake: Divide the batter evenly among the prepared cake pans. Bake for 20-25 minutes or until a toothpick inserted into the center comes out clean. Allow the cakes to cool in the pans for 10 minutes, then turn out onto a wire rack to cool completely.

Caramel Mascarpone Filling: In a mixing bowl, beat the mascarpone cheese with the powdered sugar and instant coffee granules until smooth. In a separate bowl, whip the heavy cream to stiff peaks. Fold the whipped cream into the mascarpone mixture until well combined.

Assemble the Cake: Place one cake layer on a serving plate. Spread a layer of the caramel mascarpone filling on top. Drizzle some caramel sauce over the filling. Repeat with the second layer. Place the third cake layer on top and spread the remaining filling. Drizzle more caramel sauce over the top.

Garnish: Decorate with chocolate chips or coffee beans.