Set the oven rack to the lower and upper-middle position. Preheat to 350ºF (177ºC).
Slice the bread into ¾-inch cubes and then spread in a single layer on two large sheet pans. There should be about 16 cups of cubes.
Toast the cubes in the oven until the edges are dry and crisp, about 10 minutes, gently stirring after 5 minutes. Allow to completely cool on the sheet pan while cooking the rest of the stuffing. The bread will completely dry out. Transfer 12 cups of the toasted bread to a large bowl. There will be extra bread to use as desired.
Heat a large 12-inch skillet over medium heat. Melt butter in the pan, then add in the onions and celery, saute until tender, 5 to 6 minutes. Add garlic, saute until fragrant, 30 seconds. Add sage, rosemary, thyme, salt, and pepper, stir and cook for 30 seconds. Transfer mixture to the bowl with the bread cubes.
Add parsley and garlic powder to the bread mixture and gently stir to combine.
In a medium bowl whisk together eggs and chicken stock. Pour the liquid evenly over the bread, gently stir to combine. Allow soaking for 5 minutes.
Set the oven rack to the middle position. Grease a 9x13-inch pan with vegetable oil, softened butter, or cooking spray. Evenly spread the stuffing mixture into the pan.
Cover with foil and bake for 20 minutes. Uncover and bake until the internal temperature reaches at least 144ºF (62ºC) and the surface is slightly dry, about 15 to 20 minutes. Serve the stuffing warm.
Recipe Yield: 8 cups
Serving Size: 1 cup
Substituting store-bought bread: Use 12 cups of dried bread cubes instead of the fresh bread loaf.
Using dried herbs: Use half the amount of the fresh herbs (sage, thyme, and rosemary), a total of 1 tablespoon dried. Poultry seasonings can also be used, add 1 tablespoon.
Make-ahead: Cut and dry bread up to 5 days before using, store in an airtight container. Combine all of the stuffing ingredients, cover, refrigerate, and bake within 1 day. Bake covered for 30 minutes, then remove and continue to bake until the internal temperature reaches at least 144ºF (62ºC) and the surface is dry.
Reheating: Cool the baked stuffing, cover, and refrigerate. Warm individual portions on high power in the microwave in 30-second intervals until warm. Alternatively, heat in a 300ºF (149ºC) oven until warmed through.
Make it DAIRY-FREE: Substitute olive oil for butter.
Make it GLUTEN-FREE: Use gluten-free bread.
Make it VEGETARIAN: Use unsalted vegetable stock or broth instead of chicken.