Preheat oven to 450°F. Pat beef into a 9-inch pie plate and sprinkle with 1/4 teaspoon each salt and pepper. Cook until beef browns, about 8 minutes, and remove from oven; set aside and preheat broiler.

Meanwhile, combine potatoes and half and half in a microwavable bowl. Cover with plastic wrap and turn back a corner of plastic to allow steam to escape. Microwave until hot, about 1 to 2 minutes; whisk with a fork until smooth and set aside. Microwave vegetables according to package directions; mix vegetables and remaining 1/4 teaspoon of salt into potatoes.

Pour off any accumulated juices from beef. Pat potato mixture into meat crust and sprinkle with cheese. Broil 4 inches from heating element until cheese is melted, about 2 to 3 minutes. Slice into 6 pieces and serve.