In a large pot, bring salted water to a boil. Add the pasta and cook according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the rest and set aside.
In a large skillet, heat olive oil over medium heat. Add the minced garlic and chopped onion, sauté for about 2-3 minutes until fragrant and the onion is translucent.
Pour in the diced tomatoes with their juices. Stir in the dried oregano, red pepper flakes, salt, and pepper. Let it simmer for about 5 minutes to blend the flavors. Then, add the fresh spinach and cook until wilted, about 2-3 minutes.
Add the drained pasta to the skillet with the tomato and spinach mixture. Toss well to combine, adding reserved pasta water a little at a time until you reach your desired sauce consistency.
Plate the pasta and garnish with fresh basil leaves. If desired, sprinkle with grated Parmesan cheese before serving.
Notes
Serve in a large bowl or plates, ensuring a sprinkle of fresh basil enhances both color and aroma. A drizzle of olive oil and an extra sprinkle of cheese can add a touch of elegance.