In a large bowl, toss the broccoli with Olive Oil, salt, black pepper, and garlic. Spread the broccoli in a single layer on a rimmed baking sheet.
Bake until florets are tender enough to pierce with a fork and the edges are browning, about 15 minutes. Turn once halfway through the baking process and add red pepper flakes, if using. After baking, squeeze lemon juice liberally over the broccoli before serving.