Preheat the oven to 325ºF. Spread the bread cubes out on a baking sheet. Bake, stirring occasionally, until golden and dried, 15-20 minutes. Set aside to cool.
Grease a 9x13-inch baking dish with 1 tablespoon of butter. In a large skillet, melt 4 tablespoons of butter over medium heat. Add the onions, shallot, celery, and carrots. Cook, stirring occasionally, until the onions are soft, 8-10 minutes. Add the garlic and herbs. Cook, stirring often, for 2 minutes. Add the wine and cook, uncovered, for about 5-6 minutes or until the liquid is reduced by half. Season generously with salt and pepper. Transfer to a large bowl and stir in the bread cubes and broth. Season with salt and pepper.
Transfer to the baking dish. Dot the top of the casserole with the remaining 2 tablespoons of butter. Bake for 20-30 minutes, until golden brown.
Notes
*Note: Do not use packaged bread cubes; instead, you’ll be making your own with a loaf of gluten-free bread. Depending on the bread you choose, you’ll likely need to use 1 loaf to yield 6 cups of bread cubes. Take your favorite gluten-free bread and slice into cubes, about 1-1½ inches wide.