How to Make It
In a large deep skillet, cook the bacon over moderately high heat, stirring occasionally, until crisp, 6 to 8 minutes. Transfer to paper towels to drain.
Pour off all but 2 tablespoons of the bacon fat from the skillet. Add the onion and celery and cook over moderate heat, stirring, until softened, about 6 minutes. Add the garlic and cook until fragrant, about 2 minutes. Add the kale, a handful at a time, and cook, stirring, until completely wilted and just tender, 4 to 5 minutes. Transfer the kale to a large bowl and toss with the bread.
Preheat the oven to 350°. Butter a 3-quart baking dish. In a large bowl, whisk the eggs with the milk, cream, chicken stock and salt and pepper. Pour the custard over the bread and kale, add the bacon and toss well. Transfer the bread pudding to the prepared baking dish. Press plastic wrap directly on the bread and let stand at room temperature until the custard is absorbed, about 1 hour. Remove the plastic wrap.
Bake the bread pudding for about 1 hour, or until the custard is set and the top is golden and crisp. Let stand for 20 minutes before serving.