INGREDIENTS
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cooking spray (such as Crisco®)
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1/2 cup butter
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1 onion, minced
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3 tablespoons Dijon mustard
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1 tablespoon poppy seeds
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2 teaspoons Worcestershire sauce, or more to taste
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1 (12 count) package Hawaiian sweet rolls, split, or more as needed
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1 pound sliced deli ham, or more as needed
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8 slices Swiss cheese, or more as needed