Creating One Pot Cheesy Chicken Pasta is easy when you follow these straightforward steps:

1. Heat Oil: In a large pot, heat the olive oil over medium heat.
2. Cook Chicken: Add the chicken pieces to the pot and cook until they are golden brown, approximately 5-6 minutes.
3. Add Onions and Garlic: Stir in the diced onion and minced garlic, cooking for an additional 2-3 minutes until the onion is translucent.
4. Pour in Broth and Milk: Carefully pour in the chicken broth and milk into the pot.
5. Incorporate Pasta: Add the penne pasta, Italian seasoning, salt, and pepper. Stir well to combine.
6. Bring to a Boil: Increase the heat and bring the mixture to a boil. Once boiling, reduce to a simmer and cover the pot.
7. Cook Pasta: Let it simmer for about 12-15 minutes, stirring occasionally, until the pasta is al dente and most of the liquid is absorbed.
8. Add Cheese: Once cooked, stir in the shredded cheddar cheese and grated Parmesan cheese until melted and creamy.
9. Garnish and Serve: Remove from heat, garnish with fresh parsley if desired, and serve hot.

These steps make it easy to achieve an amazing, flavorful dish with minimal effort and maximum satisfaction.