In a large skillet, heat oil over medium heat.
With the skin removed, brown chicken in oil. 2 minutes per side, flipping once.
In the slow-cooker, combine crushed tomatoes, diced tomatoes, peppers and onions spices and mix. Add the chicken from the skillet.
Cover and cook on low for 6-8 hours.
Serve over pasta and mozzarella cheese (put cheese directly on the pasta, and then top with the chicken and sauce).