Creating this flavorful dish is simple if you follow these easy steps:

1. Cook the Spaghetti: Begin by boiling a large pot of salted water. Add the spaghetti and cook it according to package instructions until al dente. Drain and set aside.

2. Prepare the Chicken: In a large skillet, heat the olive oil over medium heat. Add the diced chicken, seasoning it with salt, and pepper. Cook until the chicken is browned and cooked through, about 5-7 minutes.

3. Sauté Aromatics: Add the chopped onion to the skillet with the chicken. Sauté until the onion becomes translucent, which should take around 3-4 minutes.

4. Incorporate Garlic: Stir in the minced garlic and cook for another minute until fragrant. Be cautious not to burn the garlic as it can turn bitter.

5. Add Tomatoes and Spice: Pour in the canned diced tomatoes with green chilies along with the red pepper flakes. Stir everything together and let it simmer for about 5 minutes.

6. Combine with Spaghetti: Add the drained spaghetti to the skillet. Toss to coat the spaghetti thoroughly in the sauce.

7. Adjust Seasoning: Taste and adjust the seasoning with additional salt, pepper, or red pepper flakes based on your preference.

8. Serve Hot: Remove from heat and serve immediately, garnishing with fresh parsley or basil if desired.