Mustard Green Gratin

Mustard Green Gratin from Field of Greens
stemmed mustard greens
1 tablespoon unsalted butter, plus extra for baking dish
3 whole eggs, beaten
10 ounces ricotta cheese
2 ounces grated Parmesan (approximately 1/2 cup)
1/2 teaspoon kosher salt, plus extra for garlic and mushrooms
1/4 teaspoon freshly ground black pepper
2 cloves garlic, minced
12 ounces mushrooms, sliced
1 cup crushed round butter crackers
Preheat the oven to 375 degrees F. Remove any large stems from the greens and wash them thoroughly; do so in a sink with at least 5 inches of water. Moving the leaves around in the water and allowing them to sit for a few minutes to allow the sand or dirt to fall to the bottom of the sink. Once clean, roughly chop the greens. You should have 1 pound finished greens once they are stemmed. (Weigh the greens after stemming, but before washing.) After washing the greens, place them in a salad spinner to thoroughly dry them. Butter a 9 by 11-inch or 2 1/2-quart baking dish and set aside. In a large mixing bowl whisk together the eggs, ricotta, Parmesan, salt, and pepper. Set aside. In a large, 13 by 11-inch roasting pan set over 2 burners on medium heat, melt the butter in 1 corner of the pan. Add the garlic, mushrooms, and a pinch of salt and cook until the mushrooms give up their liquid, approximately 5 to 6 minutes. Add the greens and cook until they are wilted, approximately 3 to 4 minutes. The greens will reduce to less than 1/4 of their original volume and begin to look like thawed, frozen spinach. Remove the pan from the heat. Add the greens to the egg and cheese mixture and stir to thoroughly combine. Pour into the prepared baking dish, top with the crackers, place on the middle rack of the oven and bake for 35 to 40 minutes. Allow to cool for 5 minutes and serve.