Heat a large saucepan over medium-high heat and add the ground beef. Break it up with a meat masher or wooden spoon and cook until browned, about 5–7 minutes. Drain excess grease.
Add the salt, black pepper, chopped yellow onion, 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 4–5 minutes.
Meanwhile, microwave 1 cup of hot water in a microwave-safe bowl for 2–3 minutes. Crumble in the Knorr tomato bouillon cube and stir until fully dissolved.
Add the two 15-ounce cans of tomato sauce, the tomato paste, and the bouillon-infused hot water to the saucepan. Stir to combine, bring to a gentle boil, then reduce heat to low.
Cover and simmer for 30 minutes, stirring occasionally to prevent sticking and to blend flavors.
While the sauce simmers, cook the thick spaghetti noodles according to the package directions, then drain.
Serve the sauce over cooked spaghetti noodles.