Savory Cottage Cheese Dutch Baby with Mushrooms

0 Arrange a rack in the middle of the oven and remove any racks above it. Place a 10-inch cast iron skillet on the rack, and heat the oven to 425°F. 
1 In a large bowl, vigorously whisk together the eggs, milk, cottage cheese, flour, 1/2 teaspoon of the salt, and several grinds black pepper until no lumps remain, about 1 minute. Whisk in 1 tablespoon of the chives and 1 tablespoon of the thyme leaves. Set aside to rest while the oven finishes heating. 
2 Carefully remove the skillet from the oven and immediately add the butter. Swirl to melt, making sure it coats the bottom and up the sides of the pan. Immediately pour the batter into the hot skillet. Sprinkle with the Parmesan cheese. 
3 Bake until golden and puffed and crispy on the edges, 20 to 25 minutes. Meanwhile, heat the oil in your largest skillet over medium-high heat. Add the mushrooms, toss to coat, and do your best to arrange them in a single layer. Sear, undisturbed, until the bottoms are well-browned, about 3 minutes. Season with the remaining 1 teaspoon salt and several grinds black pepper. Sauté until browned and tender, about 5 minutes. 
4 Reduce the heat to medium. Add the garlic and the remaining 1 tablespoon thyme leaves. Sauté for 2 minutes more. Remove from the heat and stir in the vinegar. 
5 At this point, your Dutch baby should be just about ready. When it’s done, pull it out of the oven and immediately top it with the mushrooms. Sprinkle with the remaining 1 tablespoon chives and more Parmesan cheese. Slice into 4 wedges for serving.