Heat olive oil in a large pot or Dutch oven over medium-high heat. Add the chopped onion, carrot, and celery, sautéing for 5 minutes until softened. Add the minced garlic and cook for 1 minute more until fragrant.
Add the ground beef to the pot, breaking it apart with a wooden spoon. Cook for 5 to 7 minutes until completely browned. Drain any excess grease if desired.
Stir in the tomato paste, cooking for 2 minutes to deepen its flavor. Pour in the crushed tomatoes, crumbled beef bouillon cube, Worcestershire sauce, and dried oregano. Stir well to combine.
Bring the sauce to a gentle boil, then reduce the heat to low. Cover partially and simmer for at least 30 minutes, stirring occasionally.
While the sauce simmers, bring a large pot of salted water to a boil. Cook the spaghetti according to the package instructions until al dente. Reserve 1/2 cup of the pasta water, then drain the spaghetti.
Toss the cooked spaghetti directly into the bolognese sauce, adding a splash of the reserved pasta water if needed to help the sauce coat the noodles evenly.
Serve hot, generously garnished with grated parmesan cheese and fresh basil.