Preheat your oven to 350°F (175°C).
In a medium saucepan over low heat, combine the unsalted butter and chopped dark chocolate. Stir until melted and smooth, then remove from heat to cool slightly.
In a large mixing bowl, whisk together the eggs, granulated sugar, vanilla extract, brewed coffee (if using), and instant espresso granules (if using). Add the cooled chocolate mixture and mix until well combined.
Gently fold in the all-purpose flour and salt until just combined. A few lumps are fine.
Line a 9x13 inch baking pan with parchment paper, leaving overhang for easy removal later. Lightly grease the paper.
Pour half of the brownie batter into the prepared pan. Place 24 unwrapped Rolo candies evenly across the batter, then pour the remaining batter on top, spreading it to cover the Rolos.
Bake for 20-25 minutes, or until the edges look set and a toothpick comes out with a few moist crumbs.
Allow to cool in the pan for about 10 minutes, then lift out using parchment paper. Let cool completely on a wire rack before cutting into bite-sized pieces.
