Cabbage and Potato Gratin

Recipe from Martha Rose Schulman

1 large green cabbage, quartered
1 lb. potatoes, sliced and peeled (You only need peel them if they are cured. The skin on our new potatoes usually does not need to be peeled.)
2 garlic cloves
2 cups milk
1/2 cup crème fraîche
ground black pepper
4 ounces gruyere, grated (1 cup, tightly packed)
1 ounce parmesan, grated (1/4 cup)
2 teaspoons finely chopped fresh sage

Bring a large pot of water to a boil, salt generously and add the quartered cabbage and potato slices.  Reduce the heat to medium high and boil for 5 minutes.  Drain and use tongs to transfer cabbage quarters to a colander and set in the sink. 

Allow the cabbage to cool until you can handle it.  Core the wedges and cut them in half lengthwise.  Finally, slice crosswise into 1/2-inch ribbons.  Return to the colander and drain for another 5 minutes.  Place in a large bowl with the potatoes. 

Heat your oven to 375º, and butter a 3 quart baking dish.  Cut one of the garlic cloves in half and rub the dish with the cut surface.  Then slice up all the garlic and toss it in with the cabbage and potatoes.  In a bowl, whisk together the milk, crème fraîche, about 1 teaspoon salt and the pepper.  Pour it over the cabbage and potatoes, and then add both cheeses and sage, and gently toss together.  Scrape it into the baking dish. 

Bake for 1 hour and 15 minutes, or until the top is golden brown.  During the first 45 minutes, press the vegetables down into the liquid in the baking dish every 10 to 15 minutes, using the back of a large spoon.  The gratin will be bubbling when you remove it from the oven.  Wait for 10 to 15 minutes, and the liquid will finish absorbing into the potatoes and cabbage.