Preheat oven to 400°F. Spread cubed rolls and bread on baking sheets in single layers; bake in preheated oven until toasted, about 20 minutes. Let stand until ready to use.
Cook bacon in a skillet over medium until crisp, about 7 minutes. Transfer to a plate lined with paper towels to drain, reserving drippings in skillet. Add onion, carrots, and garlic to skillet; cook, stirring often, until softened, about 5 minutes. Remove skillet from heat. Crumble bacon.
Whisk together stock, butter, eggs, sage, chives, zest, salt, and pepper in a large bowl. Add toasted bread cubes, onion mixture, and crumbled bacon; toss to combine. Let stand 20 minutes. Spread mixture in a lightly greased 13- x 9-inch glass baking dish. Bake in preheated oven until top and sides are golden brown and mixture is set, about 25 minutes.