Preheat the grill or grill pan over medium-high heat and lightly oil the grates.
Season the chicken breast with salt, black pepper, and garlic powder on both sides.
Grill the chicken for about 5-6 minutes per side until fully cooked and internal temperature reaches 165°F.
While the chicken is grilling, preheat your oven to 425°F. Toss the broccoli with olive oil, a pinch of salt, and pepper on a baking tray.
Roast the broccoli in the oven for 15-20 minutes until the edges are slightly crispy and the florets are tender.
Prepare the quinoa according to package instructions if not yet cooked. If already cooked, warm it gently in a pan.
Plate the dish by slicing the grilled chicken, serving it alongside the quinoa, and topping with the roasted broccoli.
Drizzle any remaining olive oil or a squeeze of lemon if desired and serve warm.