Cut all the leaves from the artichokes, pare the hearts, and remove the fuzzy chokes. Cut the artichoke hearts into slices. Heat
Melt the remaining butter in another medium saucepan over medium heat. Add the onions and cook until translucent and tender. Add the remaining stock and heat to boiling. Reduce the heat and stir in the peas. Simmer about 3 minutes, then add the artichoke hearts and simmer a few minutes more.
Put the vegetables and just enough stock to process them in a blender or processor and puree. Pour into a bowl. Thin the soup to the desired consistency with the hot stock and season with salt and pepper. Refrigerate a few hours, then taste and adjust the seasoning. Reheat the soup. Ladle into bowls and dollop each serving with flavored whipped cream.