At its simplest, a twice-baked potato is creamy, cheesy mashed potatoes cradled in crisp, salty skin. That’s the recipe you see here: comforting, satisfying and pretty much ideal. But if you dream of other flavor combinations, like bacon, scallions and sour cream; blue cheese and chives; or cauliflower and Parmesan, just follow the recipe below and stir in any additions (reserving some for garnish) after the dairy in Step 3. Shower the top with more grated cheese if you like, then bake…