Peel back the outer leaves of cabbage. Slice 1/2 inch from bottom of cabbage so it sits flat. Next, cut a 3-in. circle in the top of the cabbage; hollow out a third of the cabbage to form a bowl.
In a large bowl, combine the spinach, sour cream, mayonnaise, onions, parsley, lemon juice and dill weed, garlic, and Parmigiano cheese. Spoon into cabbage bowl just before serving.