Potato, Spinach And Onion Gratin

Ingredients: Two pounds medium potatoes, unpeeled; two large onions, halved and thinly sliced; One-quarter cup (more if needed) chicken broth, Two tablespoons of extra virgin olive oil, Eight ounces of mushrooms, thinly sliced; One ten ounce package of frozen, chopped spinach, thawed and drained; Four garlic gloves, minced; Four teaspoons chopped fresh thyme, One-quarter teaspoon of ground nutmeg, One cup of sour cream, One-half cup of milk, Four ounces of Gruyere cheese, thinly sliced. 

Preparation: Cook potatoes in a large saucepan of boiling salted water until just tender, about thirty minutes. Drain and cool. Cut potatoes into one-third inch thick slices, removing any loose peel. Set aside.

     Combine onions and one-quarter cup of chicken broth in a large non-stick skillet. Cover and simmer over medium heat until onions are tender, stirring occasionally and adding more broth by the spoonful is mixture gets dry, about twelve minutes. Increase heat to medium high; add two tablespoons of olive oil, then mushrooms; sauté uncovered until onions are deep golden color, about ten minutes. Add spinach, garlic, thyme and nutmeg; stir three minutes. Remove from heat. Stir in sour cream and milk. Season with salt and pepper.

     Preheat oven to 350 degrees F. Lightly butter a 11x7x2-inch glass baking dish. Layer half the sliced potatoes in the prepared baking dish, overlapping slightly. Sprinkle with salt and pepper. Spread half the onion mixture over the potatoes. Repeat layering with the remaining potatoes, then the onion mixture. Top with the Gruyere cheese and bake for approximately thirty minutes. Let stand for five minutes then serve.