Begin by trimming any excess fat from the chicken breast and cutting it in half crosswise for even cooking.

In a small bowl, mix together the Italian seasoning, salt, black pepper, garlic powder, and chili powder. Rub this flavorful blend evenly over the chicken.

In a large pot, bring salted water to a rolling boil. Add the fettuccine, cooking until al dente, about 8-10 minutes. Reserve 1.5 cups of pasta water before draining.

Heat a cast-iron skillet over medium heat and add olive oil. Cook the seasoned chicken for about 3 minutes on each side until golden brown. Transfer to a plate and cover with foil.

In the same skillet, lower heat to medium-low and add butter to melt. Add minced garlic and sauté for about 1 minute until fragrant. Add reserved pasta water and chicken broth, scraping browned bits, and bring to a gentle simmer for 5 minutes.

Add the cooked fettuccine and grated Parmesan to the skillet, tossing gently to coat in the garlic sauce. Sprinkle with additional Parmesan and sliced green onion to serve.