Place the pumpkins and sweet potatoes on lightly greased baking sheets. Then drizzle them with olive oil and season them with salt and pepper.
Place the baking sheets in the oven and bake for about 30-35 minutes. Once they're finished baking, remove them from the oven and set them aside.
Simmer 1 tbsp. of oil in a large saucepan over medium heat then add in garlic and ginger. let them cook for 1 minute.
After 1 minute, add in the roasted pumpkin, roasted sweet potato, pumpkin pie spice, and dried thyme. Toss them for even coating.
Let the ingredients cook for 3-5 minutes, then add in the chicken broth and simmer. Let everything cook for 15-20 minutes.
Using an immersion blender, begin pureeing the ingredients. You can also puree them in batches using a blender and then return them to the saucepan.
Add in the milk and heavy cream and stir until they are well-blended. Heat everything thoroughly. Afterward, garnish your meal with some white truffle oil. Bon apetit!