Step 1 Score the chestnuts with an X on the flat side and roast at 550 degrees for 10 minutes. Remove from the oven and cover for a few minutes with a towel soaked in ice water and wrung out. Peel and chop. Set aside.
Step 2 Melt the butter in a large skillet over medium heat. When it is nearly melted, add the onion and cook, stirring, until the onion starts to soften, about 3 minutes. Add the celery and the bay leaves and cook, stirring, until the celery softens, about 5 minutes.
Step 3Place the bread cubes in the biggest work bowl you can find. Remove the bay leaves from the onion mixture and pour the vegetables and butter over the bread cubes. Sprinkle with the salt and sage. Pour the stock over, stirring to moisten all the bread as evenly as possible (as it starts to get wet, it will shrink and be easier to stir). Taste and adjust seasonings, then stir in the eggs until they are completely incorporated.
Step 4Spoon the stuffing into the cavity of the turkey, being careful not to pack it too tightly as the bread will expand during cooking. If it is over-packed, the stuffing will be dense and heavy. Roast the turkey as you choose. Stuffing that doesn't fit in the turkey can be placed in a casserole, moistened with a little more stock, covered tightly with aluminum foil and baked alongside the turkey. It's even better if you have a second oven; start it in a cold oven set at 350 degrees and bake until the internal temperature is 155 degrees, about 30 minutes. Leave the stuffing tightly covered until ready to serve.