Using a meat tenderizer, pound chicken breasts into 1/4 inch thick, or a uniform thickness throughout. Cut each breast in half. They are easier to handle when smaller.
Add the marinade and the chicken breasts to a large ziploc bag and marinate for 1-24 hours. If you're short on time, you can skip marinating and cook the chicken right away.
Heat 1 tablespoon of olive oil in a very large skillet or cast iron pan over medium heat and add chicken breasts. If you used the marinade, skip the extra olive oil and discard the leftover marinade.
Cook the chicken on each side for 4-5 minutes or until fully cooked and internal temperature of the chicken has reached 165° F. Remove from pan and set aside. Once the chicken has cooled enough to handle, slice into strips.
Heat 1 tablespoon olive oil in the same pan without wiping it out. Add the onions and garlic, and sauté for 2-3 minutes or until they start to soften.
Strain the canned tomatoes over a large measuring cup (will be approximately 1 cup). Add water to make a total of 3 1/2 cups liquid. Add chicken bouillon cube and stir.
Break spaghetti in half and add to the skillet, spreading out evenly. Pour 3 1/2 cups liquid over the top. Add strained tomatoes and Italian seasoning. Stir to combine.
Cook for 5 minutes, tossing occasionally to make sure any pieces of pasta that weren't hitting liquid directly, are. If liquid is fully absorbed, add an additional 1/2 cup of water.**
Cook for another 5 minutes (10 minutes total). Remove from heat and toss in salt, pepper and fresh basil leaves.
Spoon onto serving dishes, top with sliced chicken and Parmesan cheese.