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4 tablespoons unsalted butter plus more to grease pan |
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2 lb (1 k) white onion, thinly sliced (approximately 6 cups) |
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1/2 tablespoons grated orange zest |
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4 lb (2 k) sweet potatoes, peeled |
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1 cup pecans, halved and toasted |
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3 tablespoons fresh breadcrumbs |
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3 tablespoons grated parmesan cheese |