Preheat the oven to 350°F. Lightly coat a 9×9 inch baking dish with cooking spray.
Transfer the toasted sourdough cubes to a large mixing bowl. Pour the buttery vegetable mixture over the bread and gently toss it all until evenly coated.
Slowly pour the broth of your choice over the bread mixture, gently tossing it all until evenly moistened. It's very important to go slow when adding the broth; you don't want soggy bread!
1 (240g) cup chicken or vegetable broth
Tip on Using Turkey Drippings: For even more flavor, replace some or all of the broth with the pan drippings from your roasted turkey. Skim or pour off the excess fat before measuring the remaining juices. If you don't have enough, add chicken or turkey broth to reach the amount needed. Taste the drippings before adding the full amount of salt, as they can already salty.
Allow the bread mixture to rest for 5 minutes so the bread can absorb the liquid, then if needed gradually add a bit more broth only if necessary. The bread should be moist throughout but not soggy.
Transfer the stuffing into the baking dish, spreading it evenly without packing it down too firmly.
Cover the baking dish with aluminum foil and bake for 20–25 minutes.
Remove the foil after this time, and increase the heat of the oven to 400 F. Bake the stuffing for another 15–20 minutes, or until the top is golden brown and crispy.
Allow the stuffing to rest for 5–10 minutes before serving. I like to top it with more fresh herbs as a garnish!