Preheat the Oven & Prepare the Cake:
Preheat your oven to 350°F (175°C). Grease and flour a 9×9-inch baking pan or line it with parchment paper for easy removal.

Make the Cake Batter:
In a medium bowl, whisk together flour, sugar, baking powder, baking soda, and salt. In a large bowl, beat together softened butter and egg until light and fluffy. Add brewed coffee, buttermilk, and vanilla extract. Gradually add dry ingredients to the wet mixture, stirring until smooth.

Bake the Cake:
Pour the batter into the prepared pan and bake for 25-30 minutes, or until a toothpick comes out clean. Let the cake cool for 10 minutes in the pan before transferring it to a wire rack to cool completely.

Prepare the Caramel Sauce:
While the cake is cooling, make the caramel sauce. In a saucepan, combine brown sugar, butter, and heavy cream. Stir over medium heat until it simmers. Let it simmer for 3-4 minutes, stirring occasionally, until the sauce thickens. Remove from heat and stir in vanilla extract and salt. Let it cool slightly.

Prepare the Coffee Drizzle:
Whisk together brewed coffee and powdered sugar until smooth. Set aside.

Assemble the Cake:
Once the cake is cool, drizzle warm caramel sauce over the top, allowing it to soak in. Add the coffee drizzle for extra flavor.

Serve & Enjoy:
Slice into squares and serve immediately. The rich coffee and gooey caramel will melt in your mouth with every bite.