Fix the dough/crust first by whisking the dry ingredients together; flour, salt, and sugar in a food processor bowl, or just a big bowl, add cubed cold butter and mix, if you’re using your hand, you’ll need to work fast. Add the cold buttermilk and combine, if it is too dry add a tablespoon of cold water and if it is too sticky add more flour; small quantity at a time until if forms a ball. Cut into two (one bigger than the other more like ¾ and ¼) wrap with a cling film and flatten the dough into a disc form then place in a freezer to make it chill for at least 15 minutes or place in a refrigerator until it chill.
Melt butter in a large pot or skillet over medium-high heat, add the chopped onions, and garlic and stir for a couple of seconds. Add green beans, peas and carrots then seasoning with thyme, parley, salt and pepper, cook until tender making sure you’re stirring to avoid burning.
While the filling is cooking, preheat the oven to 400 degrees F and grease the pie pan with cooking spray or oil or butter then set aside.
In a small cup make slurry; add flour and some of the chicken broth make sure no lumps. Add heavy cream, broth, and the slurry it to the mixture then combine. Reduce the heat and cook until the mixture thickens.
Add the shredded chicken and combine, check the seasonings and readjust if necessary. Take it off the heat.
Roll out the other dough and carefully lift with the rolling pin and cover the pan, use your fingers and seal the edges, you can also use a fork, use any style to seal just make sure the filling well covered. Use a knife or fork to pierce the top of the pie, brush with egg wash
Bake the pie in the preheated oven for 40-45 minutes until it is golden brown.
Allow to cool down before slicing.
I had small piece of down and didn’t want it to waste so I greased a small ramekin add filling and cover with the dough and baked alongside.
I don't like my filling too thick this the way I like but you want more thick filling you could reduce the liquid or use more flour when making slurry.
Combine 1/2 cup of milk and 1/2 tablespoon of lemon juice and allow to sit for about 5 minutes before using in the recipe.