Pumpkin-squash Bisque

• 8 sugar pumpkins
• 4 pumpkins with their lids inserted on top in microwave ovens
• 1 onion
• 1/2 mashed pumpkin
• 3,800 ml saucepan
• 800 gr mashed sugar pumpkin (cooked)
• 600 ml milk
• 400 ml cans chicken broth
• 180 ml milk to blender
• 120 ml sauce