Scrub potatoes, pierce several times with a fork, and place on microwave-safe plate. Cook potatoes on High in microwave 5 minutes; turn over and cook until soft, about 5 minutes more. Scoop potato flesh into a bowl; reserve potato skins.
Cook and stir cabbage, onion, and bacon in a skillet over medium heat until vegetables are soft, about 10 minutes. Stir milk, butter, pepper, and salt into cabbage mixture; stir in potato flesh and 1/2 cup of Cheddar cheese. Cook and stir cabbage mixture, breaking up potato and mashing lightly, until milk is absorbed, about 5 minutes.
Remove pan from heat; pile potato mixture into potato skins and place stuffed potatoes in a baking dish. Sprinkle potatoes with remaining Cheddar cheese.
Bake in the preheated oven until cheese is bubbly and potatoes are heated through, about 25 minutes.