How to Make It
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. Add noodles; stir to submerge 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 and serve.
Riff #1: Swap out spaghetti for any short pasta shape, such as elbow macaroni, rotini, or shells.
Riff #2: Use fresh grape tomatoes instead, and add fresh herbs.
Riff #3: Try adding chopped skinless, boneless chicken thighs, ground beef, or ground turkey for a heartier dish.