Remove puff pastry from the freezer and allow to thaw in the fridge for a few hours before you begin.

Preheat oven to 375 degrees.

In a large skillet melt butter over medium heat. Brown chicken on both sides and cook through. Remove from the pan and set to the side. Once cool enough to handle, chop to a small dice.

Add minced cremini mushrooms, garlic, and shallots and cook down for 5 minutes. Add heavy cream, cooked chicken, and herbs de provence and stir to combine. Remove from heat.

On a well floured surface roll out puff pastry until it is smooth and flat. Cut into equal sized rectangles. I did six, but eight would also work.

Repeat the process with the second piece of puff pastry. Place six rectangles down on a large baking sheet, leaving an inch or two of room for them to expand in the oven.

Scoop mushroom filling into each rectangle. Wet finger with water and trace the outer edges of the pastry. Gently place second sheet of puff pastry over top, lining them up as well as you can. Use a fork to crimp the edges together. Crack an egg in a small bowl and add 1 tbsp. of water. Use a fork the whisk the egg into a light yellow color. Brush egg wash on top the top of each pastry.

Place in the oven and bake for around 25 minutes, or until they are golden brown.

While the pastries are in the oven, prepare the mushroom sauce.

In the same skillet, melt remaining butter. Add sliced mushrooms. Saute for 5 minutes. Add white wine and reduce for 5 minutes. Add heavy cream and reduce for an additional 5 minutes. Taste and season with salt, if necessary.

Top pastries with warm mushroom sauce and serve.