First, heat the butter in a pan until melted over medium-low in a cast iron skillet or other oven-safe skillet. Add the chopped bacon and cook until done. When the bacon is browned and crisp, add the chopped onion and garlic and cook until translucent. Add the chopped chicken and cook through. When the chicken is done, add the chopped carrots, celery and bay leaf. Increase the heat, and add chicken stock and cook down until the stock is reduced to a gravy that smoothly envelopes the other ingredients.
Remove the bay leaf and add the remaining herbs. Season with salt and pepper.
Roll out the sprouted spelt puff pastry, and cover the skillet with the dough. Cut a few vents into the crust and bake in an oven preheated to 375 º and cook until the crust is nicely browned. Allow the pie to cool for 5 to 10 minutes and serve with a fresh green salad and lacto-fermented beets.