Wash parsley, shake dry and chop the leaves of 6 stalks finely. Clean and clean the mushrooms and chop them into small pieces. Grate the Gruyère. Separate the eggs. Mix 175 g cream cheese, Gruyère, egg yolks and half of the chopped parsley and season with salt and pepper.
Beat the egg whites until stiff and fold in carefully. Spread the cheese mixture evenly on a baking tray lined with baking paper. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 12 minutes until golden brown.
Remove from the oven, turn onto a tea towel and remove paper. Roll up with the cloth to a ##roulade##. Meanwhile peel onion and garlic and dice finely. Heat 1 tablespoon of oil in a frying pan.
Sauté onion cubes and garlic for 1-2 minutes. Stir in the tomato paste and sweat briefly. Add canned tomatoes and stock and simmer for 10-15 minutes. Mash the tomatoes. Season sauce with salt, pepper and a little sugar.
Heat 2 tablespoons of oil in a pan and fry the mushrooms in portions until golden brown. Season with salt and pepper and place in a bowl. Stir 200 g cream cheese, remaining chopped parsley, breadcrumbs and milk until smooth and add to the mushrooms.
Season to taste again strongly. Roll out the cheese roulade and spread evenly with the ##mushroom## mixture, leaving about 2 cm of edge free on the outer long side. Roll up the roulade firmly.
Heat the roulade in a preheated oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: level 3) for another 5-10 minutes. Cut the roulade into slices and serve with the tomato sauce. Garnish with parsley and coarse black pepper.
You can also serve the roulade cold.