1️⃣ Build the sauce: Sauté onion and garlic in olive oil. Add crushed tomatoes, tomato paste, broth, Italian seasoning, sugar, and red pepper flakes. Season with salt and pepper, then simmer.
2️⃣ Prepare and add the meatballs: Mix meatball ingredients in a bowl, roll into 1 ½-inch balls, and place them in the simmering sauce. Cover and cook for 20–25 minutes, stirring occasionally.
3️⃣ Cook the spaghetti: Add spaghetti directly to the Dutch oven, ensuring it’s submerged. Add more broth if needed. Cover and simmer for 10–12 minutes, stirring occasionally.
4️⃣ Finish and serve: Let rest for 5 minutes. Garnish with Parmesan and fresh basil or parsley. Serve warm straight from the pot.