Clean and slice the mushrooms. Peel and halve the onion and cut into strips. Wash parsley, shake dry, pluck leaves from the stalks and chop finely, except for a few for garnishing. Mix eggs, flour, milk and half of the chopped parsley in a bowl. Season with salt and pepper.
Heat 2 tablespoons of oil in a frying pan and sauté the onions for about 3 minutes. Add the mushrooms and fry for about 5 minutes. Add double cream and simmer for about 3 minutes. Season to taste with salt and pepper. Heat a coated pan (approx. 29 cm Ø) and fry the dough in it until it forms 8 thin pancakes.
Fill the pancakes with mushroom ragout, place 2 on each plate and garnish with parsley.