Thinly slice 3 scallions. Heat 2 tablespoons butter in a large skillet; add the scallion whites, 2 ounces diced smoked ham, 1 diced celery stalk, 1/2 diced green bell pepper, and salt; cook, stirring, 6 minutes. Add 2 minced garlic cloves and a pinch of cayenne; cook 1 minute. Add 10 ounces thawed frozen black-eyed peas and 1 cup chicken broth; simmer 8 minutes. Stir in the scallion greens.