- Heat a Dutch oven or large saucepan over medium-high heat. Add oil; swirl to coat.
- Add onion and garlic to pan; sauté 3 minutes or until onion starts to brown.
- Add tomatoes, stock, oregano, and pasta, in that order. Bring to a boil.
- Stir to submerge noodles in liquid.
- Cover, reduce heat to medium-low, and cook 7 minutes or until pasta is almost done.
- Uncover; stir in salt.
- Add spinach in batches, stirring until spinach wilts. Remove from heat; let stand 5 minutes.
- Sprinkle with cheese.
Notes: You can use fresh grape tomatoes instead, and add fresh herbs. Swap out spaghetti for any short pasta shape, such as elbow macaroni, rotini, or shells. Try adding chopped skinless, boneless chicken thighs, ground beef, or ground turkey for a heartier dish.