1. Preheat the oven to 400°F. Line a large baking sheet with parchment paper.

2. Spread the broccoli and butternut squash on the baking sheet. Drizzle with 1 tablespoon olive oil, season lightly with salt and pepper, and toss to coat. Roast for 20 minutes.

3. While the vegetables roast, heat the remaining 1 tablespoon olive oil in a large oven-safe skillet over medium heat. Season the chicken with salt and pepper, then sear for about 4 minutes per side, until lightly browned. Transfer the chicken to a plate.

4. Add the butter to the same skillet. Stir in the onion, garlic, dried parsley, salt, pepper, and chicken broth. Scrape up the browned bits from the bottom of the pan and let the sauce simmer for 5 minutes.

5. In a small bowl, whisk together the half-and-half and cornstarch until smooth. Slowly stir it into the skillet and cook for 1 minute, until the sauce begins to thicken.

6. Add the chicken and roasted vegetables to the skillet, turning everything gently to coat in the creamy garlic sauce.

7. Transfer the skillet to the oven and bake for 5 to 10 minutes, or until the chicken reaches 165°F in the center.

8. Sprinkle with fresh parsley before serving, if desired.