Combine all ingredients (except melted butter, if using) and whisk or blend to thoroughly combine.
Cover and allow to sit for at least thirty minutes but up to a day ahead.
If using butter the batter should be at room temperature so that the butter doesn’t harden. While the batter is resting prepare the filling.
When ready to cook preheat a crêpe pan or large cast iron skillet to just above low. Pour batter a quarter cup at a time onto a well-buttered surface, swirl the pan or use a spoon or the measuring cup to spread the batter. Cook until set, flip and continue to cook for about another thirty seconds.
Set crêpes aside in a warm oven until ready to fill (they will start to dry out after 15-20 minutes)
Fill with cooked chicken and mushroom mixture and drizzle with crème sauce. Garnish with parmesan and parsley if desired.
Chicken and Mushroom Stuffed Buckwheat Crêpes https://www.recipefiction.com/2015/03/chicken-and-mushroom-stuffed-buckwheat-crepes.html