In a bowl mix the berries (ok to use unthawed frozen berries), sugar, arrowroot, lemon essential oil and pinch of salt.
Spoon the berry mixture onto the center of the pie crust.
Gently pinch up the sides of the pie crust to make crust bowl for the berry mix. Pull the edges in towards the center as you pinch around the outside of the pie crust. Dot the top of the galette with the pea-sized butter pieces. When completed, set aside
In a small bowl whisk the egg and a splash of coconut oil together. Paint the edges of the pie crust with the egg wash (this gives it the golden brown color). When done, sprinkle the edges with the remaining 2 tablespoons of sugar.
Place in the oven on the center rack and bake for 20-25 minutes. Remove when the crust is golden and the center is bubbly.
Allow the galette to cool before slicing and serving.