1. Preheat your oven to 400 F (200 C). On a baking sheet, toss the diced sweet potatoes with olive oil, salt, and pepper. Spread them in a single layer.

2. Roast the sweet potatoes in the preheated oven for 15-20 minutes, or until they are tender and slightly caramelized. You want them soft enough to mash easily.

3. While the sweet potatoes are roasting, carefully cut a circle from the top of each sourdough bread bowl. Use a spoon to hollow out the inside, leaving about a 1-inch thick shell. Reserve the removed bread for dipping or snacking.

4. Once the sweet potatoes are roasted, transfer them to a medium bowl. Mash them thoroughly with a fork or potato masher until smooth.

5. If using, stir the vegetable broth and heavy cream into the mashed sweet potatoes. Mix until well combined and creamy. If you prefer a thicker filling, use less broth.

6. Spoon the warm sweet potato filling generously into each hollowed-out sourdough bread bowl.

7. Garnish with fresh chives or parsley, if desired, and serve warm. The bread bowls are best enjoyed right away when the bread is still fresh and the filling is hot.