Roast the pumpkin: Place a rack in the center of the oven and preheat to Preheat oven to 350°F and line a baking sheet with parchment paper. With your sharpest knife, carefully slice the pumpkin in half from the stem to the base. With a spoon or ice cream scoop, scoop out the seeds (here is how to roast pumpkin seeds later on if you like). Drizzle 1 tablespoon of the oil over the pumpkin flesh. Sprinkle with a few pinches of salt and black pepper. Rub to evenly coat. Place on the parchment paper cut sides down and pierce the outsides with the tines of a fork. Roast until the flesh is fork tender, about 45 to 55 minutes. Set aside to cool. (See blog post above for step-by-step photos.)
To make the soup: In a Dutch oven or similar large, heavy-bottomed pot, melt the butter and the remaining tablespoon oil over medium heat. Once the butter melts, stir in the onion and 1/2 teaspoon salt. Cook, stirring occasionally, until the onion is translucent, about 8 to 10 minutes.
Stir in the garlic, ginger, cinnamon, allspice, and cayenne. Cook until fragrant, about 30 seconds.
Carefully scoop the flesh into pot (discard the skins).
With a wooden spoon, mash the pumpkin to break it up and start to combine it with the spices.
Stir in the broth. Increase the heat to high and bring the liquid to a boil. Reduce heat, partially cover, and let simmer gently for 15 minutes.
Remove the soup from the heat. Stir in the half-and-half and honey. With an immersion blender, puree the soup in the pot until it is very smooth. Or to use a regular blender, carefully transfer a few ladelfuls of the soup to a blender (do not overfill! Hot soup splatters). Blend until smooth, then transfer to a separate pot or serving bowl. Repeat with the remaining soup. Taste and add salt and black pepper as desired.
Serve hot, with a swirl of Greek yogurt and sprinkle of pepitas seeds to taste.
Notes
*You can also swap 2 (15-ounce) cans of pumpkin puree (you'll still want to blend the soup to make it smooth).
TO STORE: Leftovers of this pumpkin soup recipe can be stored in the refrigerator for up to 4 days.
TO REHEAT: Reheat on the stovetop in a pan over medium-low heat or in the microwave until warmed through.
TO FREEZE: Freeze pumpkin soup for up to 3 months in an airtight container or freezer bag. Let it thaw in the refrigerator overnight before warming.