Preheat your oven to 400°F (200°C) and prepare a baking sheet with parchment paper.
Toss the broccoli florets with one teaspoon of olive oil and a pinch of salt and pepper, then spread them on the baking sheet.
Roast the broccoli for 15-20 minutes until the edges are slightly browned and tender.
Season the chicken breast with garlic powder, salt, and pepper.
Heat a grill pan or outdoor grill to medium-high heat and lightly grease with the remaining teaspoon of olive oil.
Grill the chicken for 6-7 minutes per side, or until the internal temperature reaches 165°F.
While the chicken rests, fluff the pre-cooked quinoa with a fork.
Plate the grilled chicken alongside the quinoa and roasted broccoli, finishing with a fresh squeeze of lemon juice over the entire dish.