Macaroni and Cheese With Black Beans and Chipotle Recipe

Name: Macaroni and Cheese With Black Beans and Chipotle Recipe
Ingredients: 2 teaspoons cornstarch; 1 (12-ounce) can evaporated milk; 2 eggs; 1/2 pound elbow macaroni; 1 (15-ounce) can black beans, drained and rinsed; 2 whole chipotle chilis packed in adobo, minced, plus 2 tablespoons adobo sauce from can; 1 serrano chili or jalapeño chili, finely minced; 6 ounces block American cheese, roughly grated or diced; 6 ounces sharp cheddar cheese, roughly grated or diced; 1/4 cup roughly chopped fresh cilantro leaves and tender stems; 4 finely sliced scallions