Preheat oven to 400 degrees F.
Thoroughly rinse broccoli in warm water. Shake dry.
Place broccoli on cutting board. Use a sharp knife to cut stalk off florets. Save chunky stalk if it will be roasted with florets.
Prepare stalk for roasting. Peel away outside layer of stalk with a peeler. Slice into 1/4-inch rounds if you plan to roast them with florets. If not, skip this step and discard stalk.
Spread broccoli florets and stalk pieces on a large, rimmed baking sheet. First, combine olive oil and lemon juice (if using) in a small bowl. Thoroughly combine with a fork.
Drizzle mixture over florets in roasting pan. Sprinkle with preferred amounts of salt and pepper. Toss until evenly coated.
Roast in the preheated oven until broccoli is tender and lightly browned. Watch closely to prevent burning.
After 10 minutes, remove from oven and flip over broccoli florets and stalk pieces (if using). Return to oven for about 7 minutes. Watch closely to prevent burning.
Serve hot. Sprinkle each serving with grated Parmesan cheese (optional).