Preheat oven to 350ºF and grease a glass baking dish, set aside.

Add 1/4 cup butter to a pan and heat over medium high heat. Sauté the onions, leeks, and celery in the butter until caramelized, about 10 minutes. Add the white wine to deglaze the pan (or use 1/4 cup stock and the vinegar). Reduce until there is very little liquid. Remove pan from heat and add another 1 cup stock.

Whisk the eggs well in a large bowl and then whisk in cream. Pour the veggie and stock mixture into the bowl and stir to combine with the eggs and cream. Add the dried breads and add chicken stock until the mixture is well moistened and let stand for 10 minutes, stirring occasionally until liquid is absorbed. Add sage, parsley and thyme. Stir well to combine. Taste and adjust seasoning with salt and pepper and more herbs, if desired.

Pour into a greased baking dish, dot with the remaining 1/4 cup butter all over the top, cover with foil, and bake for 30 minutes. Remove foil and broil for a couple of minutes to crisp top.