Steam the broccoli: Place 1-2 inches of water in a saucepot with a steaming basket. Add the broccoli florets, cover, and bring the water to a boil over high heat. Steam for about 5 minutes, or until the broccoli is bright green and tender-crisp when pierced with a fork. Remove from heat immediately.
Sauté the garlic: In a large skillet, heat the olive oil and butter over medium heat. Add the minced garlic and sauté for 1-2 minutes, just until it is soft and fragrant (be careful not to burn it).
Combine ingredients: Add the steamed broccoli to the skillet with the garlic-infused oil and butter. Toss to coat evenly.
Season and finish: Season with salt and pepper. Add a squeeze of lemon juice if desired. Remove from heat and top with the grated Parmesan cheese, tossing gently until the cheese has melted.
Serve: Serve the garlic parmesan broccoli immediately while hot.