"Parmigiano-Reggiano and a generous dose of heavy cream transform butternut squash and spinach into a rich, bubbling gratin...."
INGREDIENTS
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3 pounds fresh spinach, stems discarded, or 3 (10-ounce) packages frozen leaf spinach, thawed
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5 tablespoons unsalted butter plus additional for greasing pan
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3/4 cup finely chopped onion (1 small)
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3 garlic cloves, minced
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1 1/2 teaspoons salt
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3/4 teaspoon black pepper
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Rounded 1/4 teaspoon freshly grated nutmeg
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1 cup heavy cream
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4 pounds butternut squash (2 large), peeled, quartered, and seeded
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1/2 ounce finely grated Parmigiano-Reggiano (1/4 cup)
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Special equipment: an adjustable-blade slicer