Cook the spaghetti to package directions to al dente in salted water. Right before draining, reserve about a cup of the cooking water for the sauce. Drain.
While the pasta cooks, make the sauce. Bring a large skillet to medium-high heat with a drizzle of olive oil and the onion. Stir the onion for about 4 minutes (while the pan is heating up) until translucent and soft but not brown. Add the garlic and stir for one minute.
Add the tomatoes, crushing them with your hands or a spoon as you add them to the skillet. Sprinkle the tomatoes with the sugar and as much salt and crushed red pepper as you'd like. Reduce the heat to medium-low and let the sauce simmer for about 10 minutes while the pasta cooks.
When the pasta is drained, add a few tablespoons of the pasta water to the skillet. Stir, and add the cream and spinach. Wilt the spinach just for a minute, then taste the sauce and add more salt to your preference.
Add the spaghetti to the skillet (use the pot you used to cook the pasta if the sauce skillet isn't large enough). Toss to combine, and taste one more time for seasoning; add more crushed red pepper or salt to your preference.
When the pasta is heated through, serve topped with the pine nuts and parmesan cheese. Bread to sop up the sauce probably wouldn't hurt anything. Enjoy!