Roast the bell pepper according to these instructions:
Place over flame on gas stove-top for approximately 5 minutes, using tongs to turn regularly. Wrap in clean kitchen towel and steam in a plastic bag until skin is loose and ready to fall off.
Mix together roasted green bell pepper, butter, garlic, cayenne, and salt in a bowl. Use immediately over fresh corn, on home-style bread, or refrigerate up to a week.