Make the crust: In a medium bowl, mix all the ingredients until a thick dough forms (if you place it in the fridge to chill for a few hours it rolls out better). Place on a greased sheet of parchment, and cover with another piece of greased parchment. Using a rolling pin, roll out the dough into a 1/8th inch thin crust.
Preheat oven to 400 degrees F (200 degrees C.) In a large saucepan, melt 1/2 cup coconut oil or butter. Blend in coconut flour, salt, pepper, and onion. Gradually stir in chicken broth. Cook, stirring constantly until smooth and thickened. In a separate pan, saute chopped bacon and add in mushrooms to saute in bacon fat, then stir into saucepan. Stir in chicken, asparagus, celery. Mix well and pour it into the bottom of the pie pan.
Cover the top of the pie with crust, seal edges, and cut away excess dough. Make a few small slits in the top to allow steam to escape. Bake in the preheated oven for 30 minutes, or until pastry is golden brown, and filling is bubbly.