Mix the flour, poppy seeds and salt in a bowl, create a well in the middle. Combine the milk and eggs, gradually pour into the well while mixing with a whisk.
Melt the butter, allow to cool. Add the butter, continue mixing until the batter is smooth. Cover and leave to stand at room temperature for approx. 30 mins.
Preheat the oven to 60°C, warm the platter and plates. Heat a little clarified butter in a non-stick frying pan. Pour enough batter into the pan to cover the base. Reduce the heat.
Once the underside is cooked and separates from the pan, turn the crêpe, finish cooking and keep warm. Repeat these steps with the remaining batter.
Finely chop the shallot, cut the leek in half lengthwise, cut into strips approx. 1 cm wide. Cut the mushrooms into pieces.
Heat the clarified butter. Fry the mushrooms and leek in batches for approx. 5 mins., remove from the pan. Sauté the shallot in the same pan.
Return the mushrooms and leek to the pan. Pour in the water and wine, bring to the boil and reduce to half the amount. Add the cream and heat gently, season. Fill the crêpes with the mushrooms, serve.