Melt the Chocolate: In a heatproof bowl set over gently simmering water, combine the butter and chopped dark chocolate, stirring occasionally until completely melted and smooth, about 4 to 5 minutes. Remove from heat and let cool slightly.
Whisk the Eggs: In a large bowl, whisk together the eggs and granulated sugar until pale and slightly thickened, about 2 to 3 minutes of vigorous whisking. This aerates the batter and creates a tender texture.
Combine Wet Ingredients: Pour the cooled chocolate mixture into the egg mixture, then stir in the vanilla extract, brewed coffee, and espresso granules (if using) until fully incorporated.
Mix in Dry Ingredients: In a small bowl, whisk together the flour and salt. Gently fold the dry ingredients into the wet mixture using a spatula until just combined and no flour streaks remain. Fold in the mini chocolate chips.
Prepare the Pan: Preheat your oven to 350°F. Line a 9-by-13-inch baking pan with parchment paper, allowing the edges to overhang for easy removal later.
Layer the Batter: Pour half of the batter into the prepared pan and spread evenly. Drizzle 5 ounces of caramel sauce over the batter, then top with the remaining batter, spreading gently to cover the caramel.
Add Caramel Topping: Drizzle the remaining 5 ounces of caramel sauce over the top of the batter in a decorative pattern or grid, allowing it to sink slightly into the surface.
Bake: Bake for 25 to 30 minutes, until a toothpick inserted near the center comes out with just a few moist crumbs attached. The brownies should still look slightly underbaked for that fudgy, gooey texture.