In a large pot, heat 2 tablespoons of olive oil over medium-high heat. Sauté 3 cloves of minced garlic and 1 finely chopped onion for about 2 minutes until fragrant and slightly softened. Then, add your diced celery and carrot (if using) and continue to sauté for another 3 minutes until the vegetables are tender.

Increase the heat to medium-high and add 750g of ground beef to the pot. Cook, stirring frequently, until the beef is browned and no longer pink, about 5-7 minutes.

Pour in 3/4 cup of dry red wine, allowing it to simmer rapidly for 2 minutes. This step will deglaze the pot, releasing all those delicious browned bits.

Stir in 1.2kg of crushed tomatoes, 1/4 cup of tomato paste, 1-3 teaspoons of white sugar (to taste), 2 teaspoons of Worcestershire sauce, 3 dried bay leaves, 2 sprigs of fresh thyme, and salt and pepper to taste. Cover the pot and let the sauce simmer for at least 45 minutes.

While the sauce simmers, bring a large pot of salted water to a boil. Cook 500g of spaghetti for one minute less than the package instructions, ensuring it remains slightly al dente.

Preheat your oven to 180°C (350°F). In a large casserole dish, layer half of the spaghetti mixture at the bottom. Spoon half of the remaining sauce over the pasta, followed by layers of 8-10 slices of Swiss cheese. Top this with the remaining pasta, the rest of the sauce, and finish with 2 cups of shredded mozzarella cheese.

Cover the casserole dish loosely with aluminum foil and bake in the preheated oven for 25 minutes. After that, remove the foil and bake for an additional 10 minutes until the top is bubbly and golden.

Let it cool for 10-15 minutes before slicing into your epic baked spaghetti.