Ensure the chicken pie filling is entirely cool and drain away any juice from the berries. Prepare a large baking sheet with parchment paper, and preheat the oven to 350℉.
Preparation Tips: It can be helpful to ensure you have fridge space for the entire baking sheet, if possible. Otherwise, just work quickly (within reason, no need to rush or panic), especially if your kitchen is hot. If things are starting to get melty, put it all in the fridge for 20 minutes. You will need a small dish with some water in it for gluing the pastry together, so prepare that now.I find it helpful to prepare the egg wash ahead of time so I'm not rushing to make it as I prepare the clangers for the oven. Crack the egg into a small bowl and add a splash of water. Mix well, and set it aside with your pastry brush for when you need it. Lightly flour your working surface, and pull out one of your pastry dough portions. Only work with one portion at a time to ensure the dough stays cold. Cut the dough portion into 4 equal pieces, and set two aside. Then roll out the other two into rectangles, about 4-5" wide by 7-8" long, and ¼" thick. Precision is not important here.
On one rectangle, place about ⅓-1/2 cup of the chicken pie filling on one side, leaving at least a ½" margin to the edge. Then, using a knife or bench knife, cut off about 1" of dough from the short end of one of the rectangles. Use your fingers to flatten it thin. If it is too thick, it won't cook through and will be gummy. Then use a sprinkle of water to stick the long side of it to the center of the dough rectangle, behind the chicken filling. This will create a divider that keeps the dinner and dessert sections separate. Ensure the divider is as tall or taller than the chicken filling to prevent leaks.Once the divider is in place, add ¼-1/3 cup of berry filling to the other side of the clanger, ensuring to leave at least ½" margin to the edge. Dip your fingers in water, and use it to lightly wet the entire outside edge of the clanger.
Take the second dough rectangle and gently lay it on top. Use a knife to cut off any large excesses from the edge of the clanger, but leave at least ½" of dough all the way around.
Use a fork to press the edges of the top and bottom rectangles together, sealing the clanger all the way around. Then slash the top of both sides to allow for steam to vent. I like to use different slashes to mark which side is dinner and which side is dessert. Here I have 3 slashes for dinner and 2 for dessert.
Transfer the completed clanger to your pan, and then repeat the assembly with all the others. If you have the fridge space, store the assembled clangers there while they wait for the oven.You should have 6 clangers by the end, and may have some extra dough scraps for decoration or patching. If you accidentally tear a hole in the dough, just dab some water on it and glue a pretty patch on. No one will know! Brush all the clangers with egg wash, and sprinkle turbinado sugar on the dessert section if you desire. Then bake for 35-40 minutes, until the pastry is golden brown and the filling is bubbling.
Cool on a rack for at least 10 minutes before serving.