Soak cashews in water for at least 2 hours. Drain cashews, then put them in a blender with 1 cup of the stock. Blend on high for several minutes, until the cashew cream is very smooth, with no grittiness.

Combine squash with remaining broth in a stock pot and puree with an immersion blender. Heat on medium-low until the soup is hot. Add salt, pepper, and nutmeg. Stir in cashew cream. If soup is too thick, add a bit more broth. Adjust salt and pepper to taste.