
Preheat the oven to 425°F. Line a large baking sheet with parchment paper.
Add the Brussels sprouts to a large, microwave-safe bowl and add an inch of water to the bottom. Cover with plastic wrap, poke a couple of holes into the plastic, and microwave on high until knife-tender, 5–6 minutes. Carefully remove the plastic. Strain and pat dry with paper towels.
Transfer the Brussels sprouts to the prepared parchment paper. Use the bottom of a cup or a meat mallet to smash the sprouts until flattened. Pat dry again to remove any excess moisture.
Add the olive oil, garlic powder, paprika, oregano, salt, and pepper to a small bowl. Whisk to combine.
Brush the oil mixture evenly over the sprouts and spread them out so they're not touching. Bake for 10 minutes. Sprinkle the Parmesan cheese on top, then continue baking for 10 more minutes or until golden and crispy.