1 1/2 teaspoons Kosher Salt (plus additional for non-measured seasoning)
1/4 teaspoon freshly ground Black Pepper (plus additional for non-measured seasoning)
1/3 cup Heavy Cream
1/2 cup toasted Pumpkin Seeds (for garnish – optional)
Preheat oven to 425°F and arrange a rack in the middle.
Line a baking sheet with aluminum foil. Place the squash pieces cut-side up on the baking sheet. Melt 1 tablespoon of butter and brush all of it over the stops and insides of the squash halves (alternatively, you may rub it on evenly with your fingers). Season generously with salt and pepper. Roast in oven until knife tender, about 50 minutes to one hour.
While the squash roasts, peel, core, and cut the apple into medium dice. Cut the onion into medium dice. Melt the remaining tablespoon of butter in a large saucepan or Dutch oven over medium heat. Add the apple, onion, and sage, season with salt and pepper, and cook (stirring occasionally) until softened – about 7 minutes. Remove the pan from the heat and set aside.
When the squash is ready, set the baking sheet on a wire rack until the squash is cool enough to handle. Using a large spoon, scoop the flesh into the saucepan with the sautéed apples and onions; discard the squash skins.
Add broth, water, and measured salt and pepper. Stir to combine and bring to a boil over medium-high heat. Reduce the heat to medium low and simmer, stirring occasionally and breaking up any large pieces of squash until the flavors meld – about 15 minutes. Remove the pan from the heat and stir in cream.
Using a blender, purée the soup in batches until smooth, removing the small cap (the pour lid) from the blender lid and covering the space with a kitchen towel (this allows steam to escape and prevents the blender lid from popping off). Alternatively, use an immersion blender. Taste and season with salt and pepper if needed. Serve garnished with the pumpkin seeds, if using.