Begin by gathering all your ingredients. Chop the broccoli into bite-sized pieces and dice the chicken breasts into small cubes. Season the chicken with 1 teaspoon of salt, pepper, and 1/2 teaspoon of Italian seasoning.
In a large pot, bring salted water to a boil. Add the medium shells pasta and cook according to package instructions until al dente. In the last 3-4 minutes of cooking, add the chopped broccoli to the pot. Drain the pasta and broccoli together in a colander, and set aside.
In a large skillet over medium heat, melt 2 tablespoons of butter. Add the seasoned chicken pieces and cook until browned and cooked through, about 6-8 minutes. Use a meat thermometer to check that the internal temperature reaches 165°F (75°C). Remove the chicken from the skillet and set aside.
In the same skillet, melt the remaining tablespoon of butter. Add the minced garlic, onion powder, garlic powder, and dried thyme (if using). Sauté for about 1 minute until fragrant. Pour in the chicken broth and bring to a simmer. Reduce heat and stir in the heavy cream, remaining salt, and Italian seasoning. Allow the sauce to thicken slightly.
Add the cooked chicken back to the skillet, followed by the drained pasta and broccoli. Stir everything together, allowing the pasta to absorb the creamy sauce. Gradually mix in the Parmesan cheese until melted and well combined. Taste and adjust seasoning if necessary.
Serve the Chicken and Broccoli Pasta warm, garnished with fresh parsley if desired. Enjoy every creamy bite!