Preheat the oven to 400°F (200°C). Arrange pumpkin wedges on a baking sheet, drizzle with olive oil, and sprinkle with a little salt. Roast for about 40 minutes until the pumpkin is tender and slightly caramelized around the edges. The house will fill with a warm, sweet aroma.
While the pumpkin roasts, chop the onion and garlic. In a skillet, warm a teaspoon of olive oil over medium heat, then sauté the onion and garlic until soft and fragrant—about 5 minutes—until they start to turn translucent and smell inviting.
When the pumpkin is done, allow it to cool slightly, then peel off the skin and roughly chop the flesh. Transfer the roasted pumpkin to the slow cooker along with the sautéed onion, garlic, chopped sage, apple cider, and broth. Stir everything to combine.
Cover the slow cooker and cook on low for about 6 to 8 hours, allowing the flavors to meld and the soup to develop a deep, comforting aroma. The pumpkin should become very soft and start to break down.
Once cooked, use an immersion blender to carefully blend the soup directly in the slow cooker until smooth and velvety. Alternatively, transfer the mixture in batches to a blender, then return it to the slow cooker.
Add the heavy cream to the blended soup, stirring well to create a rich, silky consistency. Taste and season with salt and pepper as needed. If the soup is too thick, stir in a splash of broth or cider to loosen it to your preferred consistency.
Keep the soup warm until ready to serve. Ladle into bowls and garnish with a small sprig of sage or a drizzle of cream for a beautiful presentation. The soup should be smooth, thick, and enveloping, with warm fall flavors richly centered in every spoonful.
