Heat the butter in a small pan then cook the garlic and chili (if using) for 2 minutes. Add the stock, bring to a boil then reduce by 3/4. Whisk in the cream then stir in the parmesan to make a sauce. Keep warm on a low heat.
Cook the broccoli in a large pan of boiling salted water until just tender. Scoop out the pan with a slotted spoon or tongs and drain. Add the gnocchi to the same boiling water and cook following pack instructions. Drain. Toss the gnocchi and broccoli with the sauce and serve in warmed bowls.