Butter, lemon, garlic and shrimp — this can’t-go-wrong combo even works on roasted spaghetti squash. The “noodles” and shrimp are tossed together, tucked back into the hollowed-out squash skins and showered with Parmesan, parsley and red pepper flakes just before serving.
Preheat the oven to 425ºF.
Cut the squash in half width-wise with a serrated knife and remove the seeds with a spoon. Brush the flesh of each half with 1 teaspoon of the oil and season with ½ teaspoon salt and a few grinds of pepper. Put the halves flesh-side down on a baking sheet and bake until the flesh can easily be flaked with a fork and the edges just turn brown, about 45 minutes.
Separate the strands of squash by scraping the flesh with a fork. Transfer the scraped strands to a large bowl. Cover with foil and keep warm. Reserve the scraped squash shells.
Heat a large nonstick skillet over medium heat. Pat the shrimp dry with paper towels and sprinkle with salt and pepper. Melt 4 tablespoons of the butter in the skillet. Add the shrimp and cook until golden pink, about 2 minutes per side. Transfer the shrimp to the bowl with the squash strands.
Return the skillet to medium heat and add 1 tablespoon of the butter. When melted, add the garlic and red pepper flakes and cook until fragrant, about 30 seconds. Stir in the wine and lemon juice. Increase the heat to high and boil until the liquid thickens slightly, about 1 minute. Remove the skillet from the heat and stir in the remaining 3 tablespoons butter and the parsley.
Pour the sauce over the shrimp and squash strands and toss to combine. Transfer the mixture back into the squash shells and top with grated Parmesan, more parsley and red pepper flakes.