Creamy Portobello Soup

Name: Creamy Portobello Soup
Ingredients: 4 tablespoons unsalted butter; 1 8-ounce ham steak, diced; 4 leeks (white and light green parts only), thinly sliced; Kosher salt and freshly ground pepper; 2 5-inch portobello mushroom caps, stemmed and chopped; 3 tablespoons all-purpose flour; 3 tablespoons dry sherry or madeira wine (optional); 2 cups low-sodium chicken broth; 1 cup half-and-half; Crusty bread, for serving (optional)