Special equipment: an immersion blender or food processor
Melt the butter in a large stockpot over medium-high heat. Add the shallots and garlic and saute, stirring occasionally, until softened, about 5 minutes. Add the mushrooms and saute until they begin to release some of their moisture and soften, about 3 minutes.
Add the white wine and simmer until most of the liquid is gone, about 5 minutes. Add the chicken stock, bring to a simmer and cook, stirring occasionally, for 20 minutes. Remove the pot from the heat and blend using an immersion blender or in batches in a food processor.
Return the soup to the heat and add the cream, 1 teaspoon salt and 1/2 teaspoon pepper. Stir to combine. Taste and add more salt and pepper as needed.
Serve with some crusty bread for dipping.
If you can't find fresh cepes, use button mushrooms as your base and add some dried cepes that you have soaked in warm water (be sure to add the soaking water too!). Frozen cepes also work well.