Cheesy Kale and Mushroom Strata

🥘 Ingredients

• sourdough or country-style bread 13 oz
• extra-virgin olive oil 2 tbsp
• crimini mushrooms 8 oz
• garlic 2 cloves
• kosher salt 1 tsp
• freshly ground black pepper ½ tsp
• unsalted butter 1 tbsp
• leeks 3
• curly kale 1 bunch
• unsalted butter 1 tbsp
• eggs 8 large
• whole grain Dijon mustard 2 tbsp
• kosher salt 1 tsp
• freshly ground black pepper ½ tsp
• whole milk 2½ cups
• Gruyère or Comté cheese 5½ oz
• Parmesan 2 oz

1. 1

   Preheat oven to 350°F. Toast sourdough or country-style bread in a single layer on a rimmed baking sheet until beginning to dry out but not yet browned, 8 minutes to 10 minutes .
2. 2

   Meanwhile, heat extra-virgin olive oil in a 12-inch cast-iron skillet over medium-high. Arrange crimini mushrooms in a single layer and cook, undisturbed, until lightly browned, about 3 minutes . Add garlic , season generously with kosher salt and freshly ground black pepper , and cook, tossing and reducing heat if needed, until mushrooms are golden brown all over, about 2 minutes .
3. 3

   Push mushrooms to one side and melt unsalted butter in the center of the skillet. Add leeks and season with salt and pepper. Cook, stirring often and mixing into mushrooms, until softened, about 5 minutes . Add curly kale by the handful, tossing to wilt slightly after each addition, and cook until all kale is mostly wilted, about 4 minutes . Transfer kale mixture to a medium bowl. Let skillet cool slightly, then wipe out and coat with remaining unsalted butter .
4. 4

   Whisk eggs , whole grain Dijon mustard , kosher salt , and freshly ground black pepper in a large bowl until no streaks remain, then whisk in whole milk .
5. 5

   Arrange half of the bread in the skillet. Cover with half of the kale mixture, then top with half of Gruyère or Comté cheese and half of Parmesan . Top with remaining bread and kale mixture; pour egg mixture over. Press down on strata with a spatula to help the bread absorb the egg. Scatter remaining Gruyère and Parmesan over the top.
6. 6

   Bake strata until golden brown and no liquid seeps out when a knife is inserted into the center, 35 minutes to 40 minutes . Let cool slightly before serving.