Heat a large saucepan or pot over medium-high heat. Add the ground beef and break it up with a meat masher or wooden spoon; cook until browned, then drain excess grease.
Add the salt, black pepper, chopped yellow onion, heaping tablespoon minced garlic, Italian seasoning, dried parsley, garlic powder, red pepper flakes (if using), Worcestershire sauce, sugar, and dried basil to the browned beef. Stir and cook until the onion is soft and translucent, about 4–6 minutes.
Meanwhile, microwave 1 cup of hot water in a microwave-safe bowl for 2–3 minutes until very hot. Crumble in the Knorr tomato bouillon cube and stir until dissolved.
Add the two 15-ounce cans of tomato sauce, the 6 ounces of tomato paste, and the hot water with dissolved bouillon to the saucepan. Stir well and bring the mixture to a boil.
Reduce heat to low, cover, and simmer the sauce for about 30 minutes, stirring occasionally.
While the sauce simmers, cook the thick spaghetti noodles in a separate pot according to package directions, then drain.
Taste the sauce and adjust seasoning if desired. Serve the sauce over cooked spaghetti noodles.
