Preheat your grill or grill pan over medium-high heat.
Season the chicken breast on both sides with salt, black pepper, and garlic powder.
Grill the chicken for about 6-7 minutes per side or until fully cooked and its internal temperature reaches 165°F. Let it rest for a few minutes before slicing.
In the meantime, preheat the oven to 425°F for roasting the broccoli.
Toss the broccoli florets with olive oil, salt, and pepper, then spread them evenly on a baking sheet.
Roast the broccoli in the oven for about 15-20 minutes, until tender and slightly crispy on the edges.
Prepare the quinoa according to package instructions if not already cooked (usually simmered in water for about 15 minutes).
Plate a serving of 1/2 cup cooked quinoa, top with sliced grilled chicken breast, and add a cup of roasted broccoli on the side.
Drizzle a tiny extra splash of olive oil over the dish if desired, and serve warm.