Salted water to cover
2 1/4 lb rutabaga, trimmed, peeled, cut in chunks
2 medium turnips, trimmed, peeled, cut in chunks
1 large sweet potato, peeled, cut in chunks
4 leeks, white and inner green parts
3 tablespoons unsalted butter
1 tablespoon flour
1/3 cup milk
1/3 cup apple cider
1/4 pound good melting cheese such as Gruyere, cut in chunks
Fresh grated Parmesan Cheese
Cook Root Vegetables:
Bring water to a boil in a large pot or Dutch oven.
Add the rutabaga chunks as they’re prepped, even if water’s not yet boiling.
Once it comes to a boil, cook for about 10 minutes before adding the turnips and sweet potato.
You’ll want to have the leeks and sauce done quite quickly after this, otherwise the sweet potatoes will turn brown. (see below)
Clean & Saute the Leeks:
Leeks collect grit between their layers. Luckily, cleaning them is easy.
First slice off the dense part of the root end, crosswise.
Remove any outer layers that are thick and tough.
Then slice off the leaf end, just where it looks like the ‘white’ ends and the ‘green’ begins.
The cut piece will probably be six inches to twelve inches long.
Now cut the leek in half, lengthwise.
Wash each half under running water, using your hand to loosely separate but still gather the layers.
Cut leek halves crosswise into 1/2 inch half-rounds for sauteeing.
Then, take the leaf end and remove another layer or two.
Inside you’ll find a tender ‘light green’ part that can also be cut into half-rounds for sauteeing.
In a large skillet or Dutch oven, melt 2 Tbsp of butter on MEDIUM, add the leeks and cook, stirring often, till soft. Set aside.
In the skillet or Dutch oven used for the leeks, melt the butter on MEDIUM.
Stir in the flour, removing all the lumps.
A spoonful at a time at first, slowly stir in the milk, stirring all the time to remove all the lumps, not adding more til the lumps are stirred out. (Press with the back of a spoon if needed.)
Add the apple cider. Stirring often, cook til the sauce thickens.
Stir in the cheese, the sauteed leeks and the cooked root vegetables.
Transfer to a baking dish. Let cool, cover and refrigerate. Return to room temperature.
Preheat oven to 375F. Uncover gratin and bake for 30 minutes or until hot and bubbly throughout. Top with Parmesan and bake another 15 minutes.