INGREDIENTS
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3 tablespoons unsalted butter, plus extra for greasing the dish
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1/4 cup finely grated Parmesan cheese, plus extra for sprinkling
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3 tablespoons all-purpose flour
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1 cup scalded milk
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1/4 teaspoon of nutmeg
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Pinch of cayenne pepper
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Kosher salt and freshly ground black pepper
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4 extra-large egg yolks, at room-temperature
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1/2 cup grated aged Cheddar cheese, lightly packed
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1 package frozen chopped spinach, defrosted and squeezed dry
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5 extra-large egg whites, at room temperature
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1/8 teaspoon cream of tartar