This really is the perfect comfort food. Dig your spoon through the crispy, golden top into the creamy bread pudding, laden with all things good, like roasted squash, spinach, sourdough bread and creamy melted cheese.
1 pound rustic sourdough bread, crusts removed and cut into 1-inch cubes
3 tablespoons unsalted butter, plus more for baking dish
3 large eggs
1 1/2 cups whole milk
1 1/2 cups heavy whipping cream
1/8 teaspoon freshly ground nutmeg
1 medium (1 pound) butternut squash, peeled, seeded and cut into 1-inch dice
1/4 cup olive oil, plus more as needed
Sea salt and freshly ground black pepper to taste
1 leek, white and light green parts, halved lengthwise then cut crosswise into 1/4-inch slices
3 cups baby spinach
1 cup shredded gruyere cheese
1/2 cup grated Parmesan cheese, divided
Preheat the oven to 400°F. Place the bread in a large bowl and set aside. Butter a 2-quart baking dish. Whisk to combine the eggs, milk, cream and nutmeg in a medium bowl. Pour the custard over the bread mixture and let sit, stirring occasionally, until absorbed, about 15 minutes. Generously season with salt and pepper.
Place the squash in a large bowl and toss with olive oil until all pieces are well coated and shiny. Season with salt and pepper. Spread the squash in an even layer on baking sheet. Transfer to the oven and roast until golden brown and tender, about 30 minutes, set aside.
In a medium skillet, melt the butter. Add the leek and cook over medium heat, stirring, until softened, about 4 minutes. Add the spinach and stir until wilted, one minute more.
Transfer the mixture to the bowl with the bread, add the roasted squash, gruyere cheese and 1/4 cup of the Parmesan, stir well.
Spoon the pudding into the prepared baking dish and bake until set and browned, about 40 minutes. Removed from the oven and preheat the broiler. Top the pudding with remaining 1/4 cup parmesan cheese. Return the pudding to the oven and broil until the cheese is browned and bubbly, about 2 minutes. Remove from the oven and serve hot.