Bake the bread cubes on a rimmed baking sheet in the oven at 400°F (200°C) until crunchy and dry, about 20 minutes, tossing halfway though.
Meanwhile, heat 1 tablespoon olive oil in a skillet over medium heat. Saute the onion until soft and slightly translucent.
Add the celery and garlic and continue to saute until soft.
Finally add the olives, sun-dried tomatoes, thyme, rosemary, and salt and pepper, and stir to combine. Remove the skillet from the heat.
Transfer the bread cubes to a large mixing bowl. Pour the onion mixture over the cubes. Toss very well to combine.
Lightly grease a 1½-quart casserole dish with a little olive oil. Transfer the bread mixture to the dish.
Pour the vegetable broth over the bread mixture, then let sit for 20 minutes while the bread absorbs the liquid.
Bake uncovered at 350°F (180°C) for 20 to 30 minutes until lightly browned on top, then serve.
Notes
*I recommend vegan gluten-free sourdough from Bread SRSLY in San Francisco. Even those who aren't gluten-free love this bread, and it freezes well. Use code veggiessavetheday for 15% off your first order.Leftover stuffing can be refrigerated in an airtight container for 3 to 4 days or frozen for up to a month.