Fill a large pot three-fourths of the way full with water. Bring to a boil. Add in Brussels sprouts and boil for 10 minutes until bright green and tender. Drain well.
Cover a baking sheet with parchment paper or foil and add the Brussels sprouts. Coat with 2 tablespoons of olive oil, and using the back of a cup, smash each sprout down so it’s somewhat flat. Season with salt and pepper. Bake for 15 minutes until golden and crisp.
To make the gremolata, mix the zest, parsley, garlic, salt and pepper.
Remove sprouts from the oven and immediately top with lemon juice. Top with gremolata and grated Parmesan for an added boost of flavor. Serve warm.