Pressure Cooker - Wash, and peel the outside rind of your squash. Remove seeds and then chop or slice into large cubes. Add to the instant pot with the broth or stock.
Chop onion and add to the pot. Add remaining ingredients except the cream. Cook on high pressure for 30 minutes, and let natural release for 10 min. Manual release remainder.
Blend contents in pot using an immersion blender until it is as smooth as you'd like. Be careful it is hot! Pour in heavy cream after your soup is blended with a bit set aside to drizzle a tad on top before serving
On Stovetop - In a Dutch oven over medium high heat melt 2 tbsp butter and add your onions. Saute until softened, then add garlic for 1 more minute. Remove seeds and rind from squash, then cube into large bite size pieces.
Pour into pot with broth and bring to a boil (add peeled chunks of carrots now too if you are adding it). Reduce heat so it is consistently boiling but not bubbling over for 12-15 minutes until squash is fork tender.
Turn to low and use an immersion blender to puree until smooth. Pour in heavy cream, add salt and pepper to taste and fold contents together. Heat until hot to your liking, turn off heat and enjoy with a bit of cool cream on top too.