Cut the top off of the pumpkin and remove the seeds and strings. Carve out the flesh of the pumpkin until the shell is about 1/2 inch thick. Be careful not to make any holes in the skin - the pumpkin is the serving bowl. Steam the pumpkin flesh in a saucepan with an inch of water, over medium heat for 20 minutes.
Remove from heat, drain and set aside to cool slightly.
In a saucepan over medium heat, cook the chicken broth until warm. Puree the pumpkin flesh and gradually stir into the pumpkin broth. Slowly bring the mixture to a boil.
Mix in the cream then season with salt, pepper and nutmeg.
Remove from heat.
Pour soup into the pumpkin shell and garnish with croutons. Top with the pumpkin cap.