Preheat your oven to 400°F and prepare a baking sheet with parchment paper.
Toss the broccoli florets with one teaspoon of 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 the broccoli roasts, rinse the quinoa under cold water and combine it with 1/2 cup of water in a small pot.
Bring the quinoa to a boil, then reduce heat to low, cover, and simmer for 15 minutes or until water is absorbed.
Season the chicken breast with garlic powder, salt, and pepper.
Heat the remaining teaspoon of olive oil in a grill pan or skillet over medium-high heat.
Grill 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.
Fluff the quinoa with a fork and stir in the lemon juice.
Plate the sliced chicken over the quinoa with the roasted broccoli on the side.