Step by step recipe:

1. 10 min.

   Prepare the filling

   
   Rinse 450 g mushrooms rapidly, then chop fairly small.
   
   Set aside.
2. 5 min.
   Peel and finely chop 50 g shallot.
3. 7 min.
   Pour 2 tablespoons olive oil into a large saucepan on medium heat. When hot, add the chopped shallot, salt and pepper, and cook for 1 minute without colouring.
   
   Add the mushrooms and fry for 5 minutes (do not salt at this stage or the mushrooms will give off a lot of liquid).
4. 1 min.
   Add 200 ml cream, salt and pepper...
5. 10 min.
   ...and leave to reduce on low heat.
   
   Check the seasoning.
6. 

   Fill the pancakes

   
   Put a small amount of filling near the edge of a pancake...
7. 
   ...start rolling it up...
8. 
   ...then fold in the sides...
9. 
   ...to finish with a neat roll.
10. 10 min.
    Prepare all the pancakes like this and lay them in an oven-proof dish.
11. 2 min.

    Bake the pancakes "au gratin"

    
    Preheat the oven to 430°F (220°C).
    
    Pour 2 tablespoons cream evenly over the pancakes and scatter 2 tablespoons grated cheese on top. Bake for about 10 minutes...
12. 10 min.
    ...until nicely browned.