Preheat the oven to 425°F (220°C) and line a large sheet pan with parchment paper or lightly grease it to prevent sticking.
Make the dressing by whisking together the oil, lemon juice, lemon zest, minced garlic, Italian herbs, salt, and pepper
Add the Brussels sprouts, onion, and gnocchi to a large bowl and toss with the dressing.
Prepare the sausage by slicing it into bite-sized pieces so it cooks evenly and browns well in the oven.
Add the sausage and Parmesan cheese to the bowl with the veggies and gnocchi, and toss again.
Spread out evenly on the baking sheet.
Roast for 25-30 minutes, stirring halfway through, until the gnocchi is golden and crisp and the sausage is golden.
Sprinkle with extra Parmesan, if desired.
Enjoy!