This comes from the Williams-Sonoma Bride & Groom cookbook. The recipe didn't state regular or unsalted butter, so I used regular and found it too salty, but my husband loved it. So, if you love salty dishes, I suggest regular butter, but if you prefer less salt in your dishes, use unsalted butter. Butter can be prepared in advance, it can be kept in the refrigerator for up to 3 days and in the freezer for 1 month. Also, recipe calls for raw shrimp, but I used flash-frozen, pre-cooked & de-shelled shrimp and had no problems. I hope you enjoy.