Heat the oven to 425°F.

Place broccoli florets, minced garlic, sliced smoked sausage, and 2 teaspoons of the chopped fresh herbs on a rimmed baking sheet. Drizzle with olive oil, then season with kosher salt and black pepper. Toss to coat, then spread the mixture into an even layer.

Roast until the broccoli is beginning to brown, about 20 minutes. Add chopped bell peppers, toss to combine, and spread back into an even layer. Return to the oven and roast until the sausage is browned and the vegetables are tender, 15 to 20 minutes more. Garnish with the remaining 1 teaspoon chopped herbs and Parmesan cheese if using.