Choose a variety of mushrooms and squash. Here we have domestic whites, chanterelles and portabellas. Do the same with the squash that is available where you live. Here I used Zuccini and acorn, I would have preferred butternut but there was none available due to the weather. Cut the large mushrooms into bite sizes ( remember they will shrink so go a little over what you want to end up with) and do the same with the squash. Blanche and refresh the squash.
Heat a little olive oil in a sturdy pan and start sauteeing the squash. Add the mushrooms according to their cooking times. chanterelles take longer than domestic for instance. While the mushrooms and squash are cooking add some chopped garlic, herbs and salt and pepper. Allow to cool.
Buy some puff pastry and roll out two sheets, enough for a bottom and a top for the amount of filling you have. Put the filling on the bottom, brush the edges with egg wash and lay the cover on top. Crimp the edges and brush with egg wash. Put the whole thing on a baking sheet and start in a hot oven about 400 or so. When it starts to color turn the heat down so it will not burn but allow it to cook all the way through. Otherwise the pastry will collapse.
The vegetables here are bok choy, Fennel bulbs, slow baked roma tomatoes and green beans.
When cooked , 30 mins or so, allow to cool a little bit and slice. Serve with vegetables and sauce of your choice.