Preheat the oven to 350 degrees F. Lightly grease a 9x13” baking dish with nonstick spray or with butter. Set the baking dish aside.
Cut the bread loaf into ¾” to 1” cubes and place the cubes in a large bowl. Set aside.
In a medium skillet over medium heat, heat the oil and butter. Once the butter is melted, add the onion, leeks, celery, and fennel. Add a pinch of salt and pepper. Stir often until the vegetables are softened, about 5 minutes. Turn the heat down if the vegetables are beginning to brown.
Add the oregano, thyme, rosemary, sage, parsley, garlic, all-purpose seasoning and salt and pepper to taste. Stir and cook for another 3 minutes.
Add the warm vegetables to the bread cubes and toss to combine. Set aside.
Pour the stock into a large bowl. Taste the stock and add salt and pepper to taste, especially if you are using unsalted or low-sodium. The stock must taste really good since the bread will be absorbing it. After seasoning, add the eggs and whisk until the eggs are completely combined and liquified in the stock.
Add about half of the stock to the bread and toss. Continue to add the remaining stock by ½ cup amounts to the bread until it is very moist, but not soaked through. The bread should still hold its shape. Toss the mixture until all the bread cubes are evenly moistened and the vegetables are evenly dispersed.
Pour the dressing into the baking dish and bake for 40 to 50 minutes, or until the top is nicely browned and a little dry-looking. You may check the internal temperature; a digital thermometer should read 165 degrees F.
Bring the dressing out of the oven and allow it to stand for about 10 minutes.
Serve very warm.