Cheesy Kale and Mushroom Strata
Ingredients
13 oz. sourdough or country-style bread, cut into 1½" cubes (about 7 cups)
2 Tbsp extra - virgin olive oil
8 oz. cremini mushrooms, sliced ¼” thick
2 garlic cloves, thinly sliced
1 tsp kosher salt, plus more
½ tsp freshly ground black pepper, plus more
2 Tbsp unsalted butter, divided
3 leeks, white and pale green parts only, halved lengthwise, sliced crosswise ¼” thick bunch curly kale, ribs/stems removed, torn into 2" pieces
8 large eggs
2 Tbsp whole grain Dijon mustard
2½ cups whole milk
5½ oz. Gruyere or Comte cheese, coarsely grated, divided
2 oz. Parmesan, finely grated, divided
Directions
Preheat oven to 350°F. Toast bread in a single layer on a rimmed baking sheet until starting to dry but not yet browned, 8-10 minutes.
Meanwhile, heat oil in a 12" cast-iron skillet over medium-high. Arrange mushrooms in a single layer and cook, undisturbed, until lightly browned, about 3 minutes. Add garlic, season generously with salt and pepper, and cook, tossing and reducing heat if needed, until mushrooms are golden brown all over, about 2 minutes. Push to one side and melt 1 Tbsp. butter in center of skillet. Add leeks and season with salt and pepper. Cook, stirring often and mixing into mushrooms, until softened, about 5 minutes. Add kale by the handful, tossing to wilt slightly after each addition, and cook, tossing often, until all of the kale is mostly wilted, about 4 minutes. Transfer mixture to a medium bowl. Cool skillet slightly, wipe it out and coat it with remaining butter.
Whisk eggs, mustard, 1 tsp. salt, and ½ tsp. pepper in a large bowl until no streaks remain. Whisk in milk. Arrange half of bread in skillet. Cover with half of kale mixture, then top with half of Gruyere and half of Parmesan. Top with remaining bread and kale mixture. Pour egg mixture over and press down with a spatula to help bread absorb the liquid. Scatter remaining cheeses on top.
Bake until golden brown and no liquid seeps out when a knife is inserted into the center, 35-40 minutes. Cool slightly before serving.
Strata can be baked 3 days ahead. Cool completely; cover and chill.
Submitted by Ann Nolan (original recipe from Deb Perelman, Bon Appétit, Nov 2018)