Fill a large saucepan with water and bring to a boil. Fill a large bowl with cold water and ice.
Add the green onions to the saucepan of boiling water and cook for 45 seconds (this is called blanching). Using a slotted spoon, remove the green onions from the boiling water and immediately put them in the bowl of ice water.
Add the peas to the saucepan of boiling water and blanch them until they are soft, about three minutes for fresh pes and one minute for frozen. Using the slotted spoon, remove all the peas from the boiling water and add them to the green onions in the bowl of ice water.
Set a large colander in the sink and drain the bowl of peas and green onions through the colander. Discard any remaining ice. Tip the pea mixture back into the bowl.
Add the milk, half cup whipping cream and salt and pepper to taste to the pea mixture. In a blender, blend the soup until smooth. If the soup is too thick, blend in the remaining cream. Pour the soup into a pot and heat gently over medium heat to serve.
Ladle the soup into warm bowls, top each serving with a dollop of crème fraiche, then garnish with bacon chips (recipe follows) and serve with crackers.
Using a very small cookie cutter, cut the bacon slices into rounds or chop them coarsely.
In a small nonstick skillet, heat the oil over medium heat. Add the bacon and cook, stirring often, until very crisp, five to seven minutes.
Using a slotted spoon, remove the bacon chips from the skillet and drain on a paper-towel-lined plate.