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 and roast for 15-20 minutes until the edges are slightly charred.
While the broccoli roasts, rinse the quinoa under cold water and place it in a small saucepan with 1/2 cup of water.
Bring the quinoa to a boil, then reduce heat to low, cover, and simmer for 15 minutes or until the water is absorbed.
Season the chicken breast with lemon juice, the remaining olive oil, garlic powder, and a pinch of salt.
Grill the chicken over medium-high heat for approximately 6-7 minutes per side or until the internal temperature reaches 165°F.
Let the chicken rest for 5 minutes before slicing, then fluff the quinoa with a fork and plate everything together.