How to Make It
In a large deep skillet, heat the olive oil over moderately high-heat. Add the garlic and shallot and cook until softened, about 2 minutes. Add the fennel, season with salt and cook, stirring occasionally, until the fennel has softened, about 3 minutes. Add the white wine, coconut milk, pumpkin puree, and red chili flakes to the pan and bring to a gentle simmer, about 8 minutes. Turn the heat to low and keep warm.
Meanwhile, in a large saucepan of salted boiling water, cook the tagliatelle until al dente. Reserve 1/2 cup of the cooking water and drain.
Add the pasta and the reserved cooking water to the pumpkin sauce and toss over moderately low heat until coated. Add the lemon juice, parmesan, and parsley to the pasta and lightly toss to combine. Season with salt and freshly ground black pepper to taste and transfer to plates. Drizzle lightly with olive oil, sprinkle with fennel fronds and serve.