Scalloped potatoes are delicious. There's no disputing that. But I find that the dish tastes a little lighter (just a little) and has a better depth of flavor with the addition of turnips. The horseradish is subtle but also gives this dish a little something extra. This Epicurious recipe (http://www.epicurious.com...) gave me the backbone of proportions etc, but I swapped out the fresh horseradish for jarred (easier to find), replaced half the potatoes with turnips, altered the cream ratio (and used a little half and half to lighten it up), and used Pecorino instead of Parm. (I like the bite of Pecorino better.) —SybilAB
Sprigs Fresh Thyme
Whole Black Peppercorns
Coffee filter or cheese cloth
Large Turnips, sliced about 1/8" thick
Large Yukon Gold Potatoes, sliced about 1/8" thick
Preheat oven to 400 and butter a gratin dish or casserole.
Make a bouquet garni by putting thyme, bay leaf, and pepper corns in a coffee filter. Tie with string or just fold up and keep at the top, seem side up.
In a large pot, combine potatoes, turnips, cream, half and half, garlic, salt, and bouquet garni. Bring to a boil, then reduce to a simmer for about 10 minutes or until the potatoes and turnips are tender. Remove from heat and remove the bouquet garni and garlic cloves. Add the horseradish.
Spread it into the buttered dish and make sure it's even. The cream should just seep up around the potatoes but not cover them. If you have extra cream, try to scoop some out so it's not too soupy.
Cover the entire top with the grated cheese. Bake until it's golden brown, it has thickened up, and the potatoes and turnips are tender. Let it sit a few minutes before serving.