My coworker asked for seconds immediately. Just 4 ingredients for this cheesy, savory bake.

For a sharper flavor, mix half Swiss and half shredded provolone or mozzarella for the top layer, keeping the total cheese amount the same. If you like a stronger sauerkraut presence, add up to 1/2 cup more sauerkraut, but be sure to squeeze it extra dry so the casserole doesn’t get watery. To lean even more low carb, choose a no-sugar-added or homemade Thousand Island or Russian-style dressing; you can even stir in a spoonful of prepared horseradish to the dressing before layering for a little kick. If you prefer a crispier, more browned cheese top, place the casserole under the broiler for 1–3 minutes at the end of baking, watching closely so it doesn’t burn. For smaller households, bake the casserole in two smaller dishes, enjoy one now, and cool and refrigerate the second for easy lunches—it reheats well and holds its layers. You can also line the baking dish with parchment if you plan to lift the whole casserole out once chilled and cut it into firm squares for stacking on low-carb crackers or toasted low-carb bread for a more traditional Reuben-style bite.