Green Corn Tamale Pie

High summer yields a special treat in Mexico and the Southwest: green corn tamales, made from mature fresh corn instead of dried masa flour. They're a labor of love — wrapping the bundles is time-consuming. But by turning their components into a pie, you get all the flavor of the traditional dish in much less time. Topped with spicy chorizo sausage and tender strips of cactus, the casserole makes a splendid entrée for supper or brunch.