01 - Bring a large pot of salted water to a boil. Add the spaghetti and cook according to package directions until al dente. Drain and set aside, reserving 1/2 cup of pasta water.
02 - Heat olive oil in a large skillet over medium heat. Add the onion and cook 4-5 minutes until softened. Stir in the garlic and cook 1 minute more.
03 - Add ground beef to the skillet. Cook, breaking up with a spoon, until browned and cooked through, about 6-8 minutes. Drain excess fat if needed.
04 - Stir in oregano, basil, and red pepper flakes. Add tomato paste and cook 1 minute to deepen flavor.
05 - Pour in crushed tomatoes and sugar. Season with salt and pepper. Simmer uncovered, stirring occasionally, for 20 minutes until sauce thickens.
06 - Toss drained spaghetti with the sauce, adding reserved pasta water as needed to reach desired consistency.
07 - Serve hot, topped with grated Parmesan, fresh basil, and a drizzle of extra virgin olive oil if desired.