Chop pumpkin: Halve the pumpkin and remove the seeds. Peel if necessary (Hokkaido pumpkin doesn’t need peeling, any other sort does). Cut the pumpkin into cubes.
Peel and chop the onion, garlic, carrots, and potatoes.
Fill the slow cooker: Place all the chopped vegetables, red chili flakes, rosemary, salt, pepper, and vegetable stock into the slow cooker.
Cook for 5 hours on low. Check: the vegetables should be tender. If they are not, give them another 30-60 minutes.
Blend the soup with an immersion blender (Note 3).
Stir in the cream.
Adjust the taste with salt, pepper, and red chili flakes. To lift the flavor, add a little lemon juice OR balsamic vinegar (to taste).