Butternut Squash Pasta with Brown Butter and Sage

Heat the oven to 425°F (220°C). Toss the squash with the olive oil, 1 teaspoon salt, and pepper, and spread on a large sheet pan in one layer. Roast 25–30 minutes, flipping once halfway, until completely tender and caramelized at the edges.

While the squash finishes, bring a large pot of well-salted water to a boil (212°F / 100°C). Cook the pasta 1–2 minutes short of the package time. Scoop out 300 ml of the starchy cooking water before draining.

Melt the butter in a large, light-colored skillet over medium heat. When it foams, add the sage leaves and fry 1–2 minutes until crisp; lift them out onto a paper towel. Keep swirling the butter for another 1–2 minutes until the milk solids turn hazelnut brown, then add the garlic and pepper flakes for 30 seconds and pull the pan off the heat.

Put two-thirds of the roasted squash in a blender with 200 ml of the pasta water and the nutmeg. Blend until completely smooth, adding more pasta water if needed to reach a thick, pourable consistency. Vent the blender lid — hot liquid expands.

Return the skillet to medium heat, add the squash sauce to the brown butter, and stir to combine. Add the pasta and toss for 1–2 minutes, adding pasta water as needed, until glossy. Off the heat, stir in the cheese and lemon juice and season. Serve topped with the reserved squash cubes, crumbled crisp sage, and walnuts.