Preheat your oven to 400°F for roasting the broccoli.
In a small mixing bowl, whisk together half of the olive oil, the lemon juice, minced garlic, and a pinch of salt and pepper to create a marinade.
Place the chicken breast in a shallow dish, coat thoroughly with the marinade, and let it rest for 15 minutes.
Toss the broccoli florets with the remaining olive oil and a dash of salt on a parchment-lined baking sheet.
Roast the broccoli in the oven for 15 to 20 minutes until the edges are slightly charred and tender.
While the broccoli roasts, heat a grill pan or outdoor grill over medium-high heat.
Grill the marinated chicken for approximately 6 to 7 minutes per side until the internal temperature reaches 165°F.
Remove the chicken from the heat and let it rest for 5 minutes before slicing into strips.
Fluff the pre-cooked quinoa and place it in a bowl, then top with the sliced chicken and roasted broccoli.