Dice the pumpkin flesh, clean the onion, garlic and celery and cut into small pieces.
Put everything except the pumpkin in a saucepan and sauté, add the pumpkin, pour in the beer and broth. Add the spices and put the lid on. Let simmer for 20 minutes.
Leave out the bacon, roast with the pumpkin seeds until crispy and set aside.
Puree the soup finely and add the sour cream. Season to taste and serve sprinkled with the bacon and seeds.