Preheat the oven to 400°F and line a large sheet pan with parchment paper.

In a small bowl, mix 1 tablespoon olive oil, garlic powder, Italian seasoning, smoked paprika, salt, and black pepper.

Place the chicken breasts on one side of the sheet pan and brush them evenly with the seasoned oil mixture.

In a large bowl, toss broccoli, bell peppers, and red onion with the remaining 1 tablespoon olive oil and a pinch of salt and pepper.

Spread the vegetables on the other side of the sheet pan in a single layer around the chicken.

Roast the chicken and vegetables for 18 to 20 minutes, until the chicken reaches 165°F at the thickest part and the vegetables are tender with lightly charred edges.

While the sheet pan roasts, add quinoa and chicken broth to a medium saucepan and bring to a boil over medium high heat.

Reduce heat to low, cover, and simmer quinoa for 15 minutes, then remove from heat and let sit covered for 5 minutes.

Fluff the quinoa with a fork and stir in the juice from half the lemon and the chopped parsley.

Slice the cooked chicken into strips and squeeze the remaining lemon half over the chicken and vegetables.

To build each plate, fill half the plate with roasted vegetables, one quarter with sliced chicken, and one quarter with quinoa.

Serve each portion with 1 tablespoon plain Greek yogurt on the side if using, and enjoy warm.