Begin by preheating your oven to 350°F.
Make sure your chicken breasts are generously seasoned with salt and pepper.
Place the chicken in a baking dish and roast for about 35 to 40 minutes until cooked through.
Allow them to cool and then shred the meat into bite-sized pieces.
In a large pot, heat olive oil over medium-high heat.
Add the chopped onions and minced garlic.
Let them sauté until soft and translucent.
Add the diced bell peppers, red pepper flakes, and chili powder to the pot.
Cook for about a minute, stirring frequently, to release their flavors.
Pour in the tomatoes, chicken stock, and shredded chicken.
Stir well and let the mixture simmer for 30 minutes to an hour.
Adjust seasoning with salt and pepper as needed.