Wilted Escarole with Country Ham and Chiles

Name: Wilted Escarole with Country Ham and Chiles
Ingredients: 1 lemon; 1/4 cup olive oil; 2 garlic cloves, very thinly sliced; 2 ounces country ham or prosciutto, cut into matchstick-size pieces (about 1/2 cup); 1 teaspoon crushed red pepper flakes; 2 heads of escarole (about 2 pounds), leaves torn into medium pieces (16 packed cups); Kosher salt and freshly ground black pepper; 2 tablespoons (1/4 stick) unsalted butter; Ingredient info: Country ham can be found at specialty foods stores and virginiatraditions.com.