Preheat the oven to 350 degrees and butter a shallow 3-quart baking dish.
Place the cubed bread in a very large bowl, or pot. Heat the olive oil in a large pan over medium-high heat.
Add the sausage and cook, stirring occasionally and breaking up with a wooden spoon.
When the sausage is browned and cooked through (Approximately 10 minutes), transfer to the bread bowl using a slotted spoon.
Add the onions and celery to the pan, and season with Salt and Pepper. Cook, stirring often, until the onions become translucent and soften (Approximately 5-7 minutes).
Then add the garlic, apple and thyme and continue cooking until the apple is soft and the onions have browned (5 minutes).
Add the onion mixture to the bread bowl.
Reduce heat to medium and add the sherry to the pan, scraping up browned bits, until the sherry is almost evaporated (Approximately 2 minutes).
Add the stick of butter to the sherry and and cook, stirring until it is melted together.
Drizzle over the bread mixture.
Next, whisk the eggs and 2 cups of the chicken stock in a medium bowl, and pour over the bread mixture.
Toss while seasoning with salt and pepper.
Add more stock ¼ cup at a time until the bread is well hydrated but not soggy.
Pour your stuffing in to your baking dish, and dot with a few pats of butter. Cover with tin foil and bake for 35 minutes.
Increase oven temperatures to 450 degrees and remove the tinfoil.
Continue to bake until the top is golden brown, approximately 20 minutes.
Allow the stuffing to rest for 15 minutes before serving.