Preheat oven to 350° F.

Cut off the top quarter of the garlic bulb to expose the pulp of the individual cloves (do not peel the cloves). Prepare a double layer of aluminum foil that is 12" square, and place the garlic bulb in the center of it. Drizzle 2 tablespoons of the olive oil over the exposed cloves and then sprinkle with a bit of salt and pepper. Bring the foil loosely up around the garlic bulb and gently twist the top shut. Set aside.

Place mushrooms and onion on a large rimmed roasting pan. Melt 2 tablespoons of the butter in a small bowl in the microwave and then add the remaining 2 tablespoons of olive oil to the butter. Stir to combine and then drizzle over mushrooms and onion. Fold to incorporate, and then sprinkle lightly with salt and pepper. Add foil-wrapped garlic bulb to pan, twisted side up. Set aside.

In a separate large rimmed roasting pan, spread the bread cubes into an even layer. Place both pans in the oven at the same time, on separate racks. Set the timer for 10 minutes and then check the bread. If it is dried out, with some crispy edges, remove the pan of bread from the oven. If it needs to bake longer, return pan to the oven for a bit and then remove from oven when the bread has dried.

Once the pan of garlic, mushrooms, and onion has been in the oven for a total of 20 minutes, give the mushrooms and onion a stir. Bake for an additional 20 to 25 minutes, or until veggies are softened and nicely caramelized, and the garlic cloves are very soft. Remove pan from oven and carefully open up the hot foil wrap on the garlic bulb to let cool.

While the two roasting pans are in the oven, brown the pork sausage in a large skillet over medium to medium-high heat on the stovetop, breaking up sausage into 1" pieces. When sausage is no longer pink, remove it to a plate.

Return skillet to stovetop and turn heat down to medium. Create the garlic toast crumb topping by first adding 1 tablespoon of butter to the pork drippings in the pan. Once melted, add panko bread crumbs, garlic powder, onion powder, salt, and pepper. Stir to combine. Cook for 5 to 10 minutes, stirring regularly, until bread crumbs are dried and crisp and just slightly golden. Remove pan from heat and set aside.

Add dried bread cubes to a very large bowl. In a medium microwave-safe bowl, melt 4 tablespoons of the butter. Squeeze the garlic cloves out of their little bulb papers, into the melted butter. Add the chicken broth. Combine ingredients with an immersion blender until smooth. Then drizzle mixture over the bread cubes, tossing to incorporate. Add sausage, mushrooms, onion, Parmesan cheese, goat cheese, and 1 tablespoon of the thyme to the bread cubes. Toss to incorporate and then transfer mixture to a large baking dish.

Sprinkle the garlic toast crumb topping over the center of the dressing, leaving the dressing exposed around the perimeter of the pan. Sprinkle with a bit of black pepper. Bake at 350° F for about 30 minutes, or until thoroughly warmed and the top is golden. If the topping starts to get too dark, lightly tent baking dish with foil. Before serving, sprinkle the remaining teaspoon of fresh thyme over the top of the dressing.