In a small bowl, whisk the flour, baking soda, and salt.
In the bowl of a stand mixer fitted with a paddle, beat the butter on medium until creamy, about one minute. Add the granulated and brown sugars and beat on medium until light and fluffy, 2 to 3 minutes.
Add the egg, vanilla, and water and mix on low to combine. Add the flour mixture and mix on low until combined. Then turn speed on mixer up to medium (a 3 or 4 on a KitchenAid Stand Mixer), and beat for 30 seconds to activate the xanthan gum that is in the gf baking flour mix.
Stir in 6 ounces of the chocolate, reserving 1 ounce to push into the top of the dough balls.
Refrigerate dough, covered, for 30 minutes. Meanwhile, preheat the oven to 350 degrees F and line two baking sheets with aluminum foil.
Form the dough into 75 gram balls (about 1/4 cup) and place 4 or 5 dough balls onto your aluminum foil lined baking sheet.
Bake for 8 minutes, until the cookies are puffed slightly in the center. Lift the side of the baking sheet up about 4 inches and gently let it drop down against the oven rack, so the edges of the cookies set and the inside falls back down. After the cookies puff up again in 2 minutes, repeat lifting and dropping the pan. Repeat a few more times to create ridges around the edge of the cookie. Bake 14-15 minutes total, until the cookies have spread out and the edges are golden brown but the centers are much lighter and not fully cooked.
Transfer the baking sheet to a wire rack; let cool completely before removing the cookies from the pan and onto another cooling rack.
Store cookies in a bag to keep fresh, up to three days.