Preheat your oven to 400°F and your grill or grill pan to medium-high heat.
Toss the broccoli florets with half of the olive oil, salt, and pepper on a baking sheet.
Roast the broccoli for 15-20 minutes until the edges are crispy and slightly charred.
Rinse the quinoa under cold water and combine with 1/2 cup water in a small pot.
Bring the quinoa to a boil, then reduce heat to low, cover, and simmer for 15 minutes.
Season the chicken breast with the remaining olive oil, lemon juice, garlic powder, salt, and pepper.
Grill the chicken for 6-7 minutes per side until the internal temperature reaches 165°F.
Fluff the quinoa with a fork and serve the sliced chicken on top with the roasted broccoli on the side.