Cut off the top of the pumpkin and remove the seeds.
Soak flaxseed in water and let it stand for at least 15 minutes.
Chop parsley, celery, garlic, walnuts and onion with a knife, grate the carrots and place in a bowl.
Add remaining ingredients, including soaked flax seeds, and mix well.
Fill pumpkins with the mixture and place them on the baking tray.
Bake for 30-40 minutes at 200°C.