Heat oven to 400º F. On a rimmed baking sheet, toss the cauliflower, sage, oil, ½ teaspoon salt, and ¼ teaspoon pepper.
Roast, tossing once, until the cauliflower is golden brown and tender, 25 to 30 minutes.
Fifteen minutes before the cauliflower is finished, cook the gnocchi according to the package directions.
Divide the gnocchi among bowls. Top with the cauliflower and Parmesan.