01 - Heat 2 tablespoons of olive oil in a large saucepan over medium heat. Add the finely chopped onion, minced garlic, diced carrot, and diced celery. Sauté for approximately 5 minutes until the vegetables are softened.
02 - Add the ground beef to the saucepan. Break it apart with a spoon and cook until it is thoroughly browned. Drain any excess fat if necessary.
03 - Stir in the dried oregano, dried basil, 1/2 teaspoon of salt, black pepper, and tomato paste. Cook for an additional 2 minutes, stirring constantly.
04 - Incorporate the crushed tomatoes, beef or vegetable broth, sugar, and the bay leaf into the saucepan. Bring the mixture to a gentle simmer, then reduce the heat to low, cover, and cook for 30 minutes. Stir occasionally. After simmering, remove and discard the bay leaf. Adjust seasoning to your preference.
05 - Concurrently, cook the spaghetti in a large pot of boiling water according to the package directions. For a more striking visual, you may add a few drops of red or pink food coloring to the boiling water.
06 - Drain the cooked spaghetti and toss it with 1 tablespoon of olive oil to prevent the strands from adhering to one another.
07 - On each serving plate, carefully twist a portion of the spaghetti to form a mound. Shape this mound to resemble a brain, incorporating folds and channels for a realistic appearance.
08 - Generously spoon the prepared Bolognese sauce over the shaped spaghetti mounds. Ensure the sauce cascades into the crevices of the 'brain'.
09 - If desired, garnish with fresh basil leaves and grated Parmesan cheese. Serve the Halloween 'Brain' Pasta Bolognese immediately.