Preheat oven to 350F.

Arrange the cubed bread onto a sheet pan in a single layer. Transfer to the oven and bake until dried out and golden, but not browned, around 8 minutes. Remove and let cool.

Preheat a sauté pan over medium-high heat. Add the olive oil and heat until shimmering. Add the sausage and, using a spatula, crumble it into small pieces. Cook, stirring occasionally, until the sausage is browned and slightly caramelized, around 12 minutes. Reserve the cooking fat in the pan and transfer the browned sausage to a large bowl. Set aside.

Add the celery and onion to the pan and season with a small pinch of salt. Cook, stirring occasionally, until the celery is slightly softened. Add the butter, if using, garlic, rosemary, sage, thyme and parsley. Cook, stirring, until the garlic is fragrant and the butter is melted, around 2 minutes. Transfer the onion mixture to the bowl with the sausage. Add the dried bread and toss to combine.

In a bowl, combine the chicken broth and eggs. Whisk until combined and smooth. Little by little, pour the broth and egg mixture into the bowl with the sausage and bread. Toss to coat and let sit at least 10 minutes so that the bread can absorb the liquid. Depending on the type of bread you use and how dry it is, you may need more or less broth. If there is excess broth, add more bread. If the mixture is too dry, add more broth.

Grease a baking dish with 2 teaspoons of olive oil and pour in the mixture. Cover the stuffing with foil and bake for 45min at 350F. Remove the foil and bake until the top is golden brown, 15-20 minutes.

Remove from the oven and let it rest 15 minutes before serving.