Step 1

Preheat oven to 425°F. Fill a large bowl with ice water.

Step 2

Bring a large saucepan of lightly salted water to a boil. Add Brussels sprouts, reduce heat to maintain a lively simmer and cook until just tender when pierced with a skewer, 8 to 10 minutes. Drain the sprouts and plunge them into the ice bath. Let stand until cool enough to handle, then transfer to a clean dish towel and pat dry.

Step 3

Spread the sprouts on a large rimmed baking sheet. Drizzle with oil; toss to coat. Space the sprouts evenly on the pan then flatten them with the bottom of a mason jar or glass. Roast for 10 minutes. Gently flip the flattened sprouts and sprinkle with Parmesan, seasoning and lemon zest. Return to the oven and bake until the cheese has melted, about 5 minutes more.