Melt the butter and add the onions. Cook until transparent.
Add the sliced mushrooms and cook.
Add the cubed broth along with the flour and stir 2 minutes.
Stir in the cream and milk vigorously not to form lumps. Season with the pepper.
Add the chicken, walnuts and tarragon and stir to combine.
You should have a very thick sauce.
Cook 2 minutes stirring.
Place 1 to 2 tablespoon chicken filling in the center of each crepe.
Place crepes, seam side down, in a buttered baking dish .
Pour the rest of the cream on top. Sprinkle the cheese.
Bake until bubbly