Begin by filling a large pot with water, adding a generous pinch of salt, and bringing it to a boil over high heat. Once boiling, add the rotini pasta and cook according to package instructions until al dente, usually around 8–10 minutes. Drain the pasta in a colander and set aside, reserving a small cup of pasta water for later.

In a large skillet, melt 2 tablespoons of unsalted butter over medium-high heat. Once the butter is bubbly and fragrant, add the diced boneless chicken breast. Season the chicken with chili powder, red chili flakes, salt, and fresh black pepper. Cook the chicken for about 5–7 minutes, stirring occasionally, until it turns golden brown and is fully cooked through.

Stir in the chopped tomatoes, green onions, and fresh parsley into the skillet with the cooked chicken. Sauté everything together for an additional 2 minutes, allowing the tomatoes to soften slightly and release their juices.

Pour in the heavy cream and chicken broth into the skillet, stirring to combine all the flavors thoroughly. Allow the sauce to simmer on medium heat for about 3–4 minutes, until it thickens slightly.

Add the drained rotini pasta into the skillet, tossing gently to coat it evenly with the creamy tomato sauce. If the mixture seems too thick, stir in a splash of the reserved pasta water.

Sprinkle a generous amount of shredded mozzarella cheese over the top of the creamy tomato chicken pasta. Cover the skillet, reduce the heat to low, and let it sit for about 2 minutes, just until the cheese melts beautifully.

Once the cheese is melted and the pasta is hot throughout, remove the skillet from the heat. Garnish the dish with additional fresh parsley for a pop of color and freshness.