In large 3 to 4 quart pot melt 2 tablespoons of butter over medium heat. Add onion and cook until translucent, about 8 minutes.
Add squash and saute for 10 minutes but do not brown. If it looks like it's browning, turn the heat down.
Add stock. Bring to a boil, reduce heat and cook until squash is tender, about 15 to 20 minutes. Remove from heat and allow to cool for 30 minutes.
Remove squash chunks with slotted spoon and place in a blender with 1 cup of the stock. Puree until smooth and return blended squash to pot.
In a small saute pan, melt the remaining butter. Add curry powder to taste and saute for a few minutes, a trick I learned from James Beard.
Add 1 cup of the stock to the curry blend and whisk well. Return the soup to medium heat and add the stock/curry mixture to the pot. Whisk well to incorporate the curry into the soup. Return to the boil, whisk the soup well, then remove from heat.
When the bubbles subside, stir in the heavy cream. Do NOT boil after adding the cream.
Taste for salt and add.
Whack the heck out of the black peppercorns.
Ladle soup into 6-8 bowls. Add a few sprinkles of the whacked black peppercorns, and serve immediately.