How to Make It
Preheat oven to 350°F. Arrange bread pieces on a large rimmed baking sheet. Bake until toasted and crisp, about 10 minutes. Let cool 5 minutes. Transfer to a large bowl.
Heat oil in a large nonstick skillet over medium. Add onion, carrot, and celery. Cook, stirring often, until crisp-tender, about 5 minutes. Add herbs. Cook, stirring constantly, until fragrant, about 1 minute. Add kale, and cook for 1 minute. Add water; cover and cook until kale is tender, about 2 minutes. Uncover and cook until liquid evaporates, about 30 seconds. Remove from heat; stir in salt and pepper. Cool slightly; transfer to bowl with bread.
Stir together broth and eggs in a medium bowl. Pour over bread mixture. Toss to coat; let stand 5 minutes. Transfer to an 11x7-inch baking dish coated with cooking spray. Bake at 350°F until crisp and golden brown on top, about 20 minutes.