2 tablespoons unsalted butter, plus more for the baking dish
1/2 lb. challah (about 1/2 loaf), cut into 1-inch cubes
3 tablespoons pure maple syrup
1 bunch (about 10 oz.) Tuscan kale, ribs removed and leaves chopped into 1-inch pieces
5 strips bacon, halved to fit in the pan (if necessary)
1 bunch scallions (white and green parts), cut crosswise into thin slices (about 1 cup)
8 large eggs
2 cups whole milk
1 cup heavy cream
1/2 teaspoon sherry vinegar
freshly ground pepper
1/2 cup coarsely grated parmigiano-reggiano
Preheat the oven to 375 degrees F. Position a rack in the center of the oven. Rub a 13x9-inch baking dish all over with a little butter.
Arrange the bread cubes in a single layer on a rimmed baking sheet and bake until lightly toasted, 8 to 10 minutes. (They will be starting to turn golden around the edges). Let the bread cubes cool for a few minutes on the sheet and then transfer them to a large bowl.
In a small saucepan, melt the 2 tablespoons butter over medium-low heat. After the butter has melted, continue to cook it, swirling the pan occasionally, until the milk solids turn nutty brown. (This can take anywhere from 3 to 6 minutes, depending on the pan you're using). Remove the pan from the heat and stir in 2 tablespoons of the maple syrup. Drizzle the brown butter-maple mixture over the bread cubes, stirring the bread as you drizzle, and toss well. Sprinkle the bread crumbs with a little salt and toss again.
Fill a wide, large pot two-thirds full of water. Add 2 teaspoons salt and bring to a boil. Add the kale to the boiling water and start timing immediately. Taste a leaf after 4 minutes. It should not be tough or rubbery. If it is, cook for 1 to 2 minutes longer. Drain the kale very thoroughly in a fine-mesh colander in the sink. Rinse with cool water until cool enough to handle. Squeeze handfuls of the kale to remove as much excess liquid as possible and then use your fingers to loosen and separate the kale so that it isn't clumped together.
In a medium heavy nonstick skillet, cook the bacon over medium-low heat until crisp and browned, 10 to 14 minutes. Transfer the bacon to a paper towel-lined plate and let cool. When the bacon is cool enough to handle, break it up into smaller pieces. Pour off half of the bacon fat. Add the scallions to the skillet and cook, stirring, until softened and beginning to brown, about 2 minutes. Add the kale, stir well to coat the kale with the scallions and pan dripping, and remove the pan from the heat.
In a large mixing bowl, whisk together the eggs, milk, cream, remaining 1 tablespoon maple syrup, sherry vinegar, several grinds of pepper, and 3/4 teaspoon salt until well combined.
Arrange half of the bread cubes in a single layer in the prepared baking dish. Top with half of the bacon (including any crumbs), half of the kale and scallion mixture, and one-third of the Parmigiano. Repeat with the remaining bread, bacon, and veggies, and another third of the cheese. Pour the egg mixture evenly over everything. (Start at one end and pour slowly back and forth). Using your hands, gently press down on the bread and veggies to force the custard to evenly surround everything. Top with the remaining Parmigiano. Let sit for about 20 minutes and gently press down again.
Bake in the preheated oven until the bread pudding has risen and is set and dry in the middle (it will be golden all over), 40 to 45 minutes. Let settle for a few minutes and serve hot or very warm.
bacon recipe courtesy of: The Fresh & Green Table: Delicious Ideas for Bringing Vegetables Into Every Meal, by Susie Middleton; San Francisco: Chronicle Books, 2012; pp. 92-93