Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Toss the broccoli florets with one teaspoon of olive oil, salt, and pepper, then spread them in a single layer on the baking sheet.
Roast the broccoli for 15-20 minutes until the edges are tender and slightly charred.
Season the chicken breast evenly with garlic powder, salt, and pepper on both sides.
Heat a grill pan or outdoor grill over medium-high heat and lightly coat 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 and broccoli finish, warm the pre-cooked quinoa in a small saucepan or the microwave until heated through.
Slice the grilled chicken into strips and serve alongside the quinoa and roasted broccoli.
Drizzle the entire plate with fresh lemon juice before serving for a bright, clean finish.