Preheat oven to 250°F.: As you set the oven, you might notice a faint dry heat that will become important for the gentle toasting of the bread . Keeping a low, steady temperature here ensures the crumbs dry evenly rather than browning too quickly, which preserves neutral toasted aroma. A common mistake is to set the oven too hot, which can brown the crusts without fully drying the interior. If your oven runs hot, check with an oven thermometer and lower heat slightly.
Cut or tear bread, including the end pieces, into 1/2- to 3/4-inch pieces, leaving soft crusts on. Spread into an even layer on two rimmed half-sheet pans.: The tactile act of tearing or cutting produces irregular surfaces that soak liquid differently, giving a pleasing mixture of textures. You will notice the crumb structure as you handle pieces, and denser bits will hold broth better. Avoid making pieces too small, as they will turn mushy when moistened. If you find a few terribly small crumbs, set them aside to use in another recipe so the stuffing keeps its structure.
Bake 50-60 minutes, until bread is lightly toasted and dry throughout. Rotate pans halfway through baking time. Let croutons cool completely at room temperature. (You should have about 1 pound of croutons.): When the pieces are in a single layer, warm air circulates and removes moisture uniformly. You want the croutons to dry through, not steam, so leave space between pieces. Overcrowding the pan traps steam and prolongs drying time, so if necessary use additional pans or bake in batches.
Raise oven temperature to 375°F and place a rack in the middle position. Butter a 3-quart gratin or 13×9 baking dish.: As the bread toasts you will hear small shifts as moisture leaves and the crumb firms up, and the aroma will turn gently nutty. Rotate the pans so both bake evenly. A common issue is stopping too early, leaving pockets of damp crumbs that collapse later; ensure the interior feels dry by breaking a piece open. You should end up with about 1 pound of croutons.
Melt 8 tablespoons butter in a skillet over medium-high heat until foaming subsides. Add celery and onion and cook, stirring frequently, until the celery is softened and the onions are translucent, about 8-10 minutes.: Increasing to a hotter baking temperature prepares the dish for a final crisp top and reliable internal warming. The butter on the dish gives added flavor and helps prevent sticking while contributing to marginal browning. If you skip buttering, the edges may cling and tear when served, so do not omit it.
Stir in 1-1/2 teaspoons kosher salt, 1 teaspoon freshly ground black pepper, sage, rosemary, thyme, and poultry seasoning. Cook for an additional 1-2 minutes until the herbs are fragrant.: The sizzling and the change in aroma as the onions sweat release sweet notes that become foundational. Watch the skillet so the aromatics do not brown too quickly; you want them softened and sweet, not caramelized. If the pan browns, lower the heat and stir more frequently to avoid a bitter finish.
In a large bowl, mix together croutons, onion and celery mixture, and parsley. Moisten with 1-3/4 cups broth or stock and let stand for a few minutes for the bread to soak up the liquid. Season to taste with additional salt and pepper.: As the herbs hit warm fat you will smell an immediate lift, a herbal brightening that signals readiness. This quick cook time allows volatile oils to bloom without becoming dull. Overcooking the herbs can make them muted, so add them toward the end and watch for fragrant steam as your cue.
In your liquid measuring cup, beat together 1/2 cup broth/stock and the eggs. Fold the mixture into the stuffing to combine and let it stand again for a few minutes to soak in. Squeeze a crouton between your fingertips; it should be moistened through but not mushy and falling apart. If the stuffing seems dry, add some of the additional liquid a little bit at a time, letting it soak in before adding more.: The first pour of broth is critical; the croutons will slurp it up and soften from the inside. Stand time lets the liquid distribute evenly. If you find dry pockets, add more broth in small increments. Avoid drowning the mixture at once, which can lead to a soggy interior instead of a tender, custardy center.
Transfer the stuffing to the prepared baking dish. Cut the remaining butter into small cubes and dot it over the top of the stuffing.: Folding in the egg enriched broth introduces a binding custard element that sets while baking and gives a silky mouthfeel. After folding, squeeze a crouton between your fingertips, it should be moistened through but not falling apart, which is the textural balance you are aiming for. A common mistake is uneven mixing, so be thorough but gentle to maintain air in the mixture.
Cover the pan with a piece of foil and bake for 30 minutes. Uncover and continue baking for 15-20 minutes, until edges are crispy and the center reads 165°F on an instant-read thermometer.: As the dish goes into the oven, those butter dots melt and baste the top, encouraging golden color and crisped edges. You will hear a soft settling as it goes in. If the butter melts too quickly and pools, your oven may be hotter than expected; place the dish a bit higher to slow browning.
Let the stuffing stand for 15 minutes at room temperature after baking. Garnish with additional chopped fresh parsley and serve with roasted turkey, chicken, and your favorite holiday sides (including a drizzle of gravy!).: Covered baking allows the interior to steam and set, while the final uncovered time crisps the edges. Look for bubbling at the edges and a gentle golden crust. If the center still reads low after uncovered time, return it for short increments to avoid overbrowning. A common pitfall is leaving the foil on too long which prevents the top from developing color.
Let the stuffing stand for 15 minutes at room temperature after baking; garnish with additional chopped fresh parsley and serve: Resting lets the custard finish setting and makes slicing or spooning cleaner. You will notice a settling of aromas and a firmer texture after rest. Serve warm alongside your main dishes. If you skip resting, the stuffing may be too loose and will not present as nicely on the plate.