Preheat oven to 400°F (200°C). On a large baking sheet, toss the cubed sweet potatoes with 2 tbsp olive oil, 1/2 tsp salt, and 1/4 tsp black pepper until evenly coated.

Spread the sweet potatoes in a single layer and roast for 25-30 minutes, or until fork-tender and slightly caramelized, flipping halfway through. Set aside.

While sweet potatoes are roasting, heat 1 tbsp olive oil in a large pot or Dutch oven over medium heat. Add the chopped yellow onion and cook for 5-7 minutes until softened and translucent.

Stir in the minced garlic and grated fresh ginger. Cook for another 1-2 minutes until fragrant, being careful not to burn the garlic.

Add the roasted sweet potatoes, vegetable broth, full-fat coconut milk, maple syrup (if using), ground cumin, ground coriander, and cayenne pepper (if using) to the pot.

Bring the mixture to a gentle simmer, then reduce heat to low, cover, and let it cook for 10 minutes to allow the flavors to meld.

Carefully use an immersion blender to blend the soup directly in the pot until completely smooth and creamy. Alternatively, transfer the soup in batches to a stand blender and blend until smooth (be cautious when blending hot liquids, only fill the blender halfway and vent the lid). Return the soup to the pot if using a stand blender.

Taste the soup and adjust seasonings with additional salt and black pepper as needed. If it's too thick, you can add a splash more vegetable broth or water.

Ladle the hot soup into bowls. Garnish with toasted pumpkin seeds, chopped fresh cilantro, or a swirl of coconut cream, if desired.