You can do this with seafood, vegetables or anything you like. This is a savory crepe so if you have a crepe recipe just take the sugar out and add some parsley or chives.
Firs you make your crepes, you can make them the day before if you like.
For the mix and the sauce: You need a breast of chicken per person and about four mushrooms.
Here we go: chop a shallot very finely (an onion will do but a shallot is better) /cut the chicken breast in largish chunks/ cut the mushrooms into fairly large pieces. Have some white wine, some chicken stock and some heavy whipping cream at the ready.
Add a little olive oil to a casserole and sauté the chicken. When it is half cooked add the shallots and cook until the shallots are translucent. Add white wine and start to reduce. Take out the chicken and let the wine reduce till almost dry. Add a little chopped garlic at this point. Add heavy cream and reduce to a sauce like consistency. Return the chicken to the sauce and add the mushrooms allow to rest for a couple of minutes until the flavors are combined.
Remove from heat and add a little chopped parsley or chives. Let cool and correct the seasoning.
With a slotted spoon remove the chicken and mushrooms and keep your sauce warm but not hot.
Fill the crepes and line them up on a flat oven proof dish. Whip up a little heavy cream very stiffly and fold it in to the sauce. Add some more fresh herbs and coat crepes.
Pass them under the broiler until you get a nice gratin effect and serve with rice.