Step 1

Preheat oven to 200ºF. Arrange the diced bread on a baking sheet and transfer to the oven for 20 minutes. Meanwhile, grease a 9x13 baking dish.

Step 2

Remove the bread from the oven and transfer to the prepared baking dish. Turn the heat on the oven to 350ºF.

Step 3

Heat the oil in the skillet over medium heat. Add the onion and cook, stirring occasionally, for 10 minutes until they just begin to deepen in color. Sprinkle with salt and reduce heat to medium-low. Continue cooking for 30 minutes or until the onions begin to caramelize. Stir them occasionally, but don't disturb them too often or else they won't caramelize.

Step 4

Melt 1 tablespoon butter into the onions and sprinkle the sugar on top. Continue cooking for 10–15 minutes until they are fully caramelized.

Step 5

Spoon half of the onions into a bowl and pour the remaining half over the diced bread and toss gently to distribute them evenly.

Step 6

Return the skillet to the stovetop over medium heat. Melt the remaining 1 tablespoon butter into the celery and cook for 7–8 minutes until it just begins to soften. Add the minced herbs and toss to coat. Cook for 1 minute until fragrant. Season with salt and pepper. Pour the celery mixture over the bread and toss gently to distribute the celery evenly.

Step 7

Combine the vegetable stock and eggs in a bowl and whisk until completely combined. Pour over the bread.

Step 8

Scatter the remaining caramelized onions on top of the stuffing. Cover with foil and transfer to the oven for 35 minutes. Remove the foil and continue baking an additional 10 minutes until the middle has set and the top is golden-brown. Remove the stuffing from the oven and turn on the broiler.

Step 9

Combine the melted butter and miso in a bowl and whisk until smooth. Pour the mixture over the stuffing.

Step 10

Transfer the stuffing to the oven under the broiler for 2–3 minutes. Keep an eye on it so that it doesn't burn, but the butter should cause the bread to crisp up and turn deep golden brown. Remove from the oven.

Step 11

Serve the stuffing warm. Keep leftovers in an airtight container for 3–4 days in the refrigerator or in the freezer for up to a month. Enjoy!