Mushroom Wellington - enough for two civilized sized squares

Alright.  I could have seriously devoured this gorgeous perfect little appie, but refrained and brought it instead to my bil's 40th birthday party.  It is easy and succulent.  Clean and then chop up mounds (maybe 5 or 6 small packages) of mixed and white or brown mushrooms.  I used portabello, as well as shitake, and some more weird ones I got at No Frills.  Additionally I chopped up 1/2 a large white onion - but feel free to chop up a whole large one, it will only add to it's delish-ous-ness.  Put about 1/4 of butter into a medium hot large frying pan and add the mushrooms and the onions and stir over heat until succulently soft.  Then add 1/4 of red wine, or more if you like, together with 1/2 a round of Boursin cheese, or add 1/2 cup of philly cream cheese or laughing cow if you wish.  I also added a few sprigs of rosemary for a nice woodsy compliment to the robust mushroom and wine mixture.  Salt and pepper and cook until most of the liquid has disappeared.  Cool down.  Then roll out puff pastry into a square (I bough already rolled out ones) and put onto a cookie sheet.  Spread 1/2 the mushroom mixture over the puff pastry to 2 cm of the edge and top with another puff pastry square the same size.  Seal the edges with a fork and cover the wellington with egg yolk so it will turn out gorgeously brown and shiny.  Put into a 375 degree oven for about 1/2 an hour.  Keep an eye on it so it doesn't get too brown - but just nice and toasty like a California girl's skin...that will melt your Popsicle, oh oh, California girls are irresistible.....Katy Perry.