Heat olive oil in a large pot over medium heat.
Add chicken strips and cook until browned on both sides.
Stir in garlic and cook for about 1 minute until fragrant.
Add diced tomatoes, chicken broth, oregano, salt, and pepper. Stir well.
Bring to a boil, then add spaghetti. Push pasta into the liquid as it softens.
Reduce heat, cover, and simmer for 12 to 15 minutes until pasta is tender.
Stir in spinach and let it wilt into the pasta.
Serve warm, topped with grated parmesan cheese.