Step 1: Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Step 2: Toss the cubed sweet potatoes and apples with olive oil, salt, and pepper on the baking sheet. Spread them in a single layer.
Step 3: Roast for 30-35 minutes, or until the sweet potatoes are tender and starting to brown at the edges.
Step 4: In a large pot, sauté the diced onion in a bit of oil over medium heat until translucent, about 5 minutes. Add the garlic and ginger, cooking for another minute until fragrant.
Step 5: Add the roasted sweet potatoes and apples to the pot, then pour in the vegetable broth and nutmeg.
Step 6: Bring the mixture to a boil, then reduce heat and simmer for 10 minutes to allow the flavors to combine.
Step 7: Use an immersion blender to blend the soup until completely smooth. Stir in the heavy cream and adjust seasoning with salt and pepper.
Step 8: Serve the roasted sweet potato and apple soup hot, garnished with toasted pumpkin seeds and a swirl of cream.