In a small bowl, whisk together 1 tablespoon of olive oil, lemon juice, minced garlic, oregano, salt, and pepper.
Place the chicken breast in a shallow dish and pour the marinade over it, ensuring it is well coated. Let it marinate for at least 15 minutes.
Preheat your grill or grill pan over medium-high heat and preheat the oven to 400°F.
Toss the broccoli florets with the remaining 1 tablespoon of olive oil, salt, and pepper on a baking sheet.
Roast the broccoli in the oven for 15-20 minutes until the edges are slightly charred and tender.
While the broccoli roasts, place the marinated chicken on the grill and cook for 6-7 minutes per side, or until the internal temperature reaches 165°F.
In a small dry skillet over medium heat, toast the pumpkin seeds for 2-3 minutes until they are fragrant and lightly golden.
Slice the grilled chicken into strips.
Assemble the bowl by placing the cooked quinoa at the base, topped with the roasted broccoli and grilled chicken.
Garnish with the toasted pumpkin seeds and an extra squeeze of lemon if desired.