Preheat your oven to 400 degrees F (200 C) and line a large baking sheet with parchment paper.
Scrub your sweet potatoes and cut them in half lengthwise. Arrange them cut side down on your tray. Add the onion, cut side down, the broccoli florets, and the unpeeled garlic to the same tray. (Use two trays if you cannot fit everything in one.)
Drizzle the vegetables with avocado oil OR vegetable broth for oil free. Use your fingers or a silicone brush to rub the liquid over the potato skin. Then sprinkle everything with salt and pepper.
Bake for 25-30 minutes, until your sweet potatoes are easily pierced with a fork, and the remaining veggies are nicely roasted and golden brown. Remove from the oven.
Optional: Reserve some of the smaller pieces of broccoli for a garnish.
Add the roasted vegetables (except the pieces you reserved for garnish) and all remaining ingredients to a pot and use an immersion blender to puree until smooth. OR, transfer to a stand blender and blend in batches. Use caution when blending hot liquids and do not overfill the blender. Taste and adjust for salt and pepper, if needed.
Serve your broccoli and sweet potato soup with the reserved roasted broccoli pieces, croutons, and cashew cream, if desired.
Notes
Use sweet potatoes that are narrow and long. Wide potatoes will take much longer to cook.Do your best to cut your sweet potatoes in equal halves for even cooking.If you prefer a thinner soup, add an additional cup of broth.Transfer the roasted vegetables to a pot and use an immersion blender to puree them so you can blend everything in one batch.Leftovers keep for 3-4 days in the refrigerator or freeze airtight in a freezer-safe container for up to 3 months.