Adjust oven racks to upper- and lower-middle positions and heat oven to 350 degrees. Line 2 cookie sheets with parchment paper. Whisk cookie dough flour, xanthan gum, cocoa powder, baking powder, salt and instant coffee in medium bowl; set aside.
In a large glass bowl, microwave chocolate and butter at 50 percent power for 2 minutes. Stir and continue heating until melted, stirring once every additional minute. Set aside to cool slightly.
Whisk sugars into melted chocolate mixture, then whisk in eggs, one at a time, and vanilla.
With a rubber spatula, fold in dry ingredients, stirring to combine. Stir in chocolate chips.
Working with 1 ½ tablespoons of dough at a time, roll into balls and place 1 ½ inches apart on prepared baking sheets.
Bake cookies until edges have just begun to set but centers are still very soft, about 10 minutes, switching and rotating baking sheets halfway through baking.
Cool cookies on sheets about 10 minutes; transfer cookies to wire rack and cool to room temperature.
Recipe by Allons-Eat! at https://www.allonseat.com/gluten-free-chocolate-fudge-cookies/