Arrabbiata means angry in Italian and is used describe pasta sauces made with hot chile peppers. We tossed the spicy sauce with orecchiette, but you can use any shape pasta you have on hand.
Bring large pot of lightly salted water to boiling.
Meanwhile, heat oil in medium-size saucepan. Add onion; cook 5 minutes, being careful not to brown the onion. Add garlic and water; cook 2 minutes.
Stir diced tomatoes, tomato sauce, red-pepper flakes, oregano and ground red pepper into saucepan; simmer, uncovered, stirring occasionally, 15 minutes.
Meanwhile, add orecchiette to boiling water; cook until al dente, tender but still firm.
Slice spinach. Add to sauce; cook 5 minutes. Add salt and pepper.
Drain pasta; transfer to large serving bowl.
Pour sauce over pasta. Sprinkle with Parmesan cheese. Serve warm.