Preheat your oven to 300°F. Grease well a 9-inch x 13-inch baking dish and set it aside.
First, make the vegetable bouillon. In a small bowl, place the nutritional yeast flakes, minced dried onion, garlic powder, dried parsley, dried thyme, and optional turmeric, and whisk to combine. Set the bowl aside.
Toast the bread.
Tear or slice the gluten free bread into roughly 1-inch pieces. Place them on a rimmed baking sheet.
Place the baking sheet in the center of the 300°F oven, and bake for 30 to 40 minutes or until dried out and lightly browned.
Continue to bake until the bread begins to shrink in size slightly and feels dry to the touch. It may take longer than 40 minutes depending on how moist the bread was at the start.
Stir at least once halfway through baking, to ensure even baking. Remove from the oven and set aside to cool.
Cook the aromatics.
In a medium-size, heavy-bottom saucepan, heat the butter and olive oil over medium heat until the butter is melted.
Add the onion, celery, salt, pepper, vegetable bouillon, and poultry seasoning or herbs de Provence, and stir to combine.
Reduce the heat to medium-low, cover and cook, stirring occasionally, until the onions and celery are fork-tender (about 10 minutes). The vegetables shouldn’t be mushy or even browned.
Increase the oven temperature to 350°F.
Combine the stuffing ingredients and bake.
Transfer the vegetable mixture to a large, heat-safe mixing bowl. Add the cooled toasted bread cubes, and mix to combine.
Whisk together the eggs and stock until smooth. Add the egg mixture to the large mixing bowl, and toss carefully to coat.
Add the optional shredded Parmigiano-Reggiano, and mix gently until just combined.
Transfer the mixture carefully to the prepared 9-inch x 13-inch baking dish. Press it gently into an even layer.
Scatter the final (optional) 2 tablespoons of cubed butter evenly across the top of the stuffing. Cover the baking dish securely with aluminum foil.
Bake at 350°F for 30 minutes. Uncover, and continue to bake until the eggs are set and the stuffing is golden brown all over (about another 30 minutes).
When it’s done, the stuffing will feel relatively firm when pressed gently with a finger in a thick portion. The top edges will be crisped but not dark. Serve warm.
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Notes
Nutritional yeast.If you don't have nutritional yeast, you can try replacing it with a bit of finely grated Parmesan cheese. You can also replace the homemade vegetable bouillon with 2 tablespoons or 2 cubes of packaged gluten free chicken or vegetable bouillon. Herb Ox and Edward & Son’s Not Chick’N brands are gluten free.About the bread.I like to use my recipe for gluten free Japanese milk bread for this recipe, but I have also had a lot of success with my basic white gluten free bread recipe. The trick is to make sure that you toast the bread until it's just beginning to brown lightly in spots, and begins to shrink in size.You can also use packaged gluten free bread. Slice the bread into cubes as large as you can make them, and be sure to toast them in the oven a bit extra so they don't fall apart during baking.Poultry seasoning or herbs de ProvenceTo make your own herbs de Provence, combine 1 tablespoon dried thyme + 2 teaspoons dried marjoram + 2 teaspoons dried savory + 1 teaspoon dried rosemary + 2 teaspoons dried lavender (optional) + 1/2 teaspoon dried sage.To make your own poultry seasoning, combine 1/2 teaspoon dried parsley + 1 teaspoon dried sage + 1/2 teaspoon dried thyme + 1/2 teaspoon dried marjoram + 1/2 teaspoon rosemary.Nutritional information is an estimate per serving assuming that the whole dish is divided into 5 equal portions. It is created as a courtesy using online nutrition calculators and is not to be relied upon.