Anyone who visits Moscow is probably familiar with this dish, because it's on nearly every Russian restaurant menu. Most often it comes to the table in individual ceramic ramekins or small copper pans. The mushrooms make the dish , so choose flavorful ones like cèpes, shiitake, or chanterelles, using them in combination with crimini or button mushrooms, if you like. Russian sour cream is thinner and milder than its American counterpart. Crème fraîche is a good substitute.
3 lbs. assorted mushrooms, cleaned, stemmed, and sliced
1 tbsp. flour
1/3 cup sour cream or crème fraîche
Salt and freshly ground black pepper
8 oz. emmentaler cheese, grated (to yield about 2 cups)
1. Preheat broiler. Melt half the butter in a large skillet over medium-high heat. Meanwhile, toss mushrooms and flour together in a large bowl. Add half the mushrooms to the skillet and sauté, stirring often, until they are soft and have released their liquid, 3–4 minutes. Transfer mushrooms to a medium bowl and repeat process with remaining butter and mushrooms.
2. Return skillet to medium-low heat. Add mushrooms and any accumulated juices and sour cream or crème fraîche, stir to combine, and cook until hot, 2—3 minutes. Season to taste with salt and pepper.
3. Transfer mushroom mixture to a wide 4-cup heatproof baking dish or pan and evenly sprinkle top with cheese. Broil casserole until cheese is melted and lightly browned and bubbling on top. Serve immediately.