Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine the brewed coffee, brown sugar, granulated sugar, vegetable oil, eggs, and vanilla extract. Whisk until well combined and the sugars are dissolved—about 1-2 minutes.

In another bowl, sift together the flour, baking powder, and salt.

Gradually add the dry mixture to the wet mixture, folding gently with a spatula until just combined.

Pour half the batter into a greased 9x13 inch baking pan. Drizzle half of the caramel sauce over the batter, then add the remaining batter on top. Finally, swirl the remaining caramel sauce into the top layer.

Place the pan in the preheated oven and bake for 40-45 minutes or until a toothpick inserted in the center comes out clean.

Allow the cake to cool in the pan for about 15 minutes. Cut into squares to serve warm or at room temperature.