Make 4 plasts from the ready-made dough, cover the baking form with them (bottom and sides). Chop finely onion, saute with diced bacon on low heat. Place the filling on the dough. Whisk egg with cream, season with salt, pepper and nutmeg. Pour over the onion filling without reaching the edges (it will rise). Bake in the oven at 180 degrees Celsius for 25-30 minutes. Serve warm or cold with glass of wine.