Preheat oven to 375° Cut squash in half lengthwise. Using a spoon, scoop out and discard the seeds and dark orange stringy flesh. Place squash cut side down on to a baking sheet. Note that you want the squash to lay perfectly flat, so you can get some caramelization going for best flavour. If they won't all lay flat, use two baking sheets if necessary and rotate their position in the oven half way through roasting. Roast in pre-heated oven for 60-70 minutes or until very tender and soft when you press on the top of the squash.
Remove from oven and using a spatula, flip the squash halves over and allow to cool a few minutes. Using a spoon, scoop all the roasted squash flesh out and in to a bowl, being careful not to take any of the skin. Discard squash skins. If making the soup immediately, measure out the amount of cooked squash needed for the soup and set aside. Any extra squash can be refrigerated or frozen and used for another purpose.
In a large soup pot, large saucepan or Dutch oven, melt butter over medium heat. Add diced onion and cook, stirring, until onion has softened and is translucent, but not browned. Add the measured roasted squash. Add the chicken broth and shredded apple. Stir to combine well. Add the fresh thyme sprig. Bring to a light boil over medium-high heat, stirring occasionally, then reduce heat to medium-low and allow soup to gently simmer, uncovered, for 20-30 minutes to blend the flavours.
REMOVE THYME SPRIG and discard. Using an immersion blender (or alternately in small batches in a blender) puree the soup well until smooth. In the soup pot, add the maple syrup and the heavy cream to the pureed soup. Stir well to combine and allow to cook over medium-low heat a few minutes to warm through.
Taste soup. Add salt as needed and some freshly ground pepper. You don't want to be skimpy with the salt! Salting well is the key to bringing out all the great flavours in this soup. Maple syrups vary in intensity. If you don't notice a subtle maple taste in the soup, add a bit more maple syrup, as needed. Serve warm garnished with drops of heavy cream and fresh thyme leaves. If you like, use a skewer to run through the drops of cream to make a pretty design.
Make-Ahead: Make this soup ahead and refrigerate for several days ahead. Rewarm on the stove-top over low heat. If soup has thickened, thin with a bit of additional chicken broth.Makes 6 full size servings or would serve 8-10 as an appetizer-sized soup.Be sure to read the Ingredient and Cook's Notes above the recipe card for more tips, options, substitutions and variations for this recipe!