Preheat your oven to 400°F (200°C) and prepare a baking sheet with parchment paper.
Toss the broccoli florets with half of the olive oil, salt, and pepper, then spread them on the baking sheet.
Roast the broccoli for 15-20 minutes until the edges are slightly charred and tender.
While broccoli roasts, season the chicken breast with the remaining olive oil, lemon juice, garlic powder, salt, and pepper.
Heat a grill or grill pan over medium-high heat and cook the chicken for 6-7 minutes per side, or until the internal temperature reaches 165°F.
Let the chicken rest for 5 minutes before slicing it into strips.
Warm the pre-cooked quinoa if necessary and fluff it with a fork.
Assemble the bowl by placing the quinoa at the base, topped with the sliced grilled chicken and the roasted broccoli.