Preheat oven to 400 F. Place the Boursin cheese block in the center of a baking dish. Arrange the chicken breasts on either side of the cheese.
Add the cherry tomatoes, broccoli florets, and chopped onion to the dish. Drizzle with olive oil and sprinkle with salt, pepper, and garlic powder to taste.
Place the baking dish in the preheated oven and bake for about 30 minutes, or until the chicken is cooked through and the vegetables are tender.
While the chicken and veggies are baking, prepare the quinoa according to the package instructions. Typically, this involves rinsing the quinoa and cooking it in a pot with water in a 2:1 ratio (2 cups of water for 1 cup of quinoa) until the water is absorbed and the quinoa is fluffy. You can also do chicken broth instead for flavor.
Once the chicken and veggies are done, remove the dish from the oven. Take out the chicken breasts and either shred or slice them into bite-sized pieces. Add the chicken back into the baking dish along with the cooked quinoa. Mix everything well to combine.
If desired, garnish with chopped basil before serving.