In a large saucepan or Dutch oven, heat 2 tablespoons of olive oil over medium-low heat. Add in 1 finely chopped shallot, 2 minced garlic cloves, and 1 sliced celery stalk. Sauté for about 5 minutes until the shallots are translucent and fragrant, stirring occasionally to prevent browning.

Stir in 4 cups of diced pumpkin and cook for an additional 5 minutes, allowing the pumpkin to soften slightly. If using fennel, add it now and sauté for 3 more minutes until everything is tender and aromatic.

Increase the heat to high and add 1.5 pounds of ground beef, breaking it apart with a wooden spoon. Cook until browned, about 10 minutes, stirring occasionally to ensure that all sides of the meat are nicely seared.

Once browned, mix in 1 teaspoon of smoked paprika, 1 teaspoon of dried thyme, sage, marjoram, chili flakes, salt, and pepper to taste. Pour in 1.75 cups of beef broth along with 1 bay leaf and bring the mixture to a gentle simmer for about 10 minutes.

Add 3 cups of puréed tomatoes and 1 tablespoon of tomato paste to the pot. Stir well to combine and cover the pan, allowing the sauce to simmer for another 10 minutes until the pumpkin is tender but still retains its shape.

While the sauce simmers, cook 14 ounces of pasta according to package instructions until al dente. Once cooked, reserve a cup of pasta water, then drain the pasta.

Toss the cooked pasta with the Pumpkin Beef Bolognese sauce, adding a bit of reserved pasta water if needed for a smoother consistency. Serve with a generous dollop of whipped ricotta on top, garnished with fresh thyme and a sprinkle of chili flakes.