Heat oven to 425 F and arrange 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 the butter and brush all of it over the tops and insides of the squash halves. Season generously with salt and pepper. Roast until knife tender, 50 minutes to an hour. 

Meanwhile, peel, core and cut the apple into a 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, a scoop the flesh into the saucepan with sage, apples and onions; discard the squash skins. 

Combine the broth, water and measured salt and pepper, stir to combine and bring to a simmer over medium-high heat. Reduce the heat to medium low and simmer for 10-15 minutes then remove from heat. 

Combine the liquid ingredients with the vegetables in a blender or food processor and process until smooth.

Add the mixture back to your pan and add the heavy cream then heat until warm. 

Top with Toasted Pumpkin Seeds