Heat 1 tablespoon of olive oil in a large skillet or grill pan over medium-high heat.
Add broccolini in a single layer and cook for 3-4 minutes per side until charred and tender-crisp.Remove from the pan and set aside. Lower the heat to medium and add the remaining 1 tablespoon olive oil to the same pan. Sauté garlic slices for 1-2 minutes until golden and fragrant.
Add chili flakes to the garlic and cook for 30 seconds, stirring constantly. Return the charred broccolini to the pan, toss to coat with the garlic and chili mixture, and season with salt and pepper.
Transfer to a serving plate and drizzle with lemon juice if desired. Serve warm.
