Step 1: Preheat your oven to 350°F (175°C) to ensure even baking for your brownie bites.
Step 2: In a medium saucepan over low heat, combine the unsalted butter and chopped dark chocolate, stirring until melted and smooth. Remove from heat and let cool slightly.
Step 3: In a mixing bowl, whisk together the eggs, granulated sugar, vanilla extract, brewed coffee, and instant espresso granules until well blended. Add the cooled chocolate mixture and stir until combined.
Step 4: In another bowl, whisk together the all-purpose flour and salt. Gradually add to the wet ingredients, folding gently until just combined; do not overmix.
Step 5: Spray your mini muffin tin with non-stick spray or line with parchment paper.
Step 6: Fill each muffin cup halfway with batter, place a Rolo candy in the center, and top with more batter to cover the candy.
Step 7: Bake for 10-12 minutes, until edges are set and center remains soft. They will continue to cook as they cool.
Step 8: Cool in the pan for 5 minutes before transferring to a wire rack. Serve warm, optionally topped with whipped cream and chocolate sprinkles.