1 Rotisserie chicken
8 oz Sliced white mushrooms
3 Tbs butter
1/4 Cup all purpose flour
1 Cup milk (or half and half)
2 Sheets puff pastry
Salt, pepper and other spices to taste
2 eggs and a splash of water

Heat oven to 385F or 190C.
Debone the chicken and chop into small pieces. 
Beat the eggs with a bit of water till foamy.
Fry the mushrooms in the butter till soft.
Sprinkle the flour over the mushrooms and stir till all the butter is absorbed.
Slowly add the milk and simmer gently till the sauce is thick.
Stir in the chopped chicken and spices to taste, let it simmer for a minute or two
Remove from the stove and let the mixture cool down completely.
Sprinkle some flour on the work surface and gently roll out the puff pastry so that you add an inch or two to the dimensions. Use a large cookie cutter, or saucer for bigger pies, and press out circles. 
Brush edges of bottom pastry with the egg-wash
Put 1 1/2 tbs cold filling in center of circle.
Gently stretch the top circle between your fingers to make sure it fits over the filling, use a fork to “seal” the edges.
I use a silicone baking sheet and bake for about 20 minutes till golden brown and nicely puffed.

Tip : You can flash-freeze unbaked pies (no egg-wash), then wrap well and keep in freezer. To bake from frozen, brush with egg-wash and bake at 350F or 165C till golden brown – about 40 minutes. Check after 30 mins. to make sure they don’t get too dark.

You can also bake this as one big pie. Same procedure. I usually spray my dish with a tiny bit of cook ‘n spray, followed by the pastry which I don’t trim and edges brushed with egg wash. Then the filling, top pastry, more egg wash, decorations, “vents”. 365F or 180C – 20 to 30 minutes.