Cook the pasta as instructed on the package. Reserve 1 cup of pasta water before draining.

In a large straight-sided skillet over medium heat, heat oil. Melt the butter and add scallion, onion, and garlic, and cook, stirring frequently, until vegetables are softened but not golden, 6 to 8 minutes.

Add tomato paste and cook, stirring constantly, until slightly darkened in color and toasted, about 2 minutes.

Pour in vodka and bring to a boil. Cook, stirring occasionally, until vodka is reduced by about three-quarters, about 2 minutes. Stir in pumpkin puree, parmesan, water, cream, nutmeg, and salt until the cheese is melted and the mixture is smooth and combined.

Add pasta to the skillet. Add 1/2 cup pasta water, stir to combine, and bring to a boil. Add pasta and stir until pasta is well coated with sauce, adding more pasta water 1 tablespoon at a time if necessary to thin the sauce; season with salt and red pepper flakes.

Serve and sprinkle parmesan and some basil on top.