Preheat oven to 375 degrees F.
Stack 2 or 3 slices of the bread on a cutting board and cut them into 1-inch thick slices. Cut the slices crosswise into 1-inch cubes. Repeat with remaining bread. You should have about 10 to 11 cups of bread cubes.
Spread the cubed bread on a rimmed baking sheet and bake for 12 minutes, or until golden brown and well toasted, tossing about halfway through the cooking time.
While the bread is toasting (but keep your eye on it), melt the butter in a large skillet. Add the onion, celery, and carrot. Turn the heat up to MEDIUM-HIGH and cook, stirring frequently, for about 8 to 10 minutes, or until tender. If the butter or veggies begin to brown, reduce the heat under the skillet a little. Add the garlic and parsley and cook and stir for another minute or two. Reduce heat to MEDIUM-LOW and add the rosemary, sage, thyme, marjoram, salt and pepper. Mix well to combine then remove from the heat.
Remove the bread from the oven and reduce the oven temperature to 350 degrees F. Coat a 13- x 9-inch baking dish (or slightly smaller dish) with nonstick cooking spray.
Transfer the toasted bread to a large mixing bowl, spoon the cooked vegetables over the bread and mix well. Add the beaten egg and stir to combine. Add 1½ cups of broth and mix well. Add as much of the remaining broth as desired so that the stuffing is very moist but not super soggy (I used very close to 2 cups total).
Transfer the stuffing to the prepared baking dish. Cover the dish with foil and bake, covered, for 35 to 40 minutes until warmed through or until the internal temperature reaches 165 degrees F. For a crispy topping, remove the foil during the last 5 to 10 minutes of the baking time, or place under the broiler for a couple of minutes before serving.
Remove cover and fluff the stuffing with a spoon and serve.