Sear the Chicken: Heat the olive oil in a large pot or Dutch oven over medium-high heat. Season the chicken pieces with salt and pepper. Add the chicken to the pot and cook until browned on all sides. Remove the chicken from the pot and set aside. It does not need to be cooked through at this point.
Sauté Aromatics: Add the chopped onion to the pot and cook until softened, about 3-5 minutes. Add the minced garlic and cook for another minute until fragrant.
Combine Ingredients: Return the chicken to the pot. Add the pasta, marinara sauce, chicken broth (or water), oregano, and red pepper flakes (if using). Stir well to combine, making sure the pasta is submerged in the liquid.
Cook the Pasta: Bring the mixture to a boil, then reduce heat to low, cover, and simmer for 15-20 minutes, or until the pasta is cooked through and the liquid has been absorbed. Stir occasionally to prevent sticking.
Add Cheese:
