• Preheat your oven to 325°F.
• Line a rimmed baking sheet with unbleached parchment paper and set it aside.

Melt the chocolate and butter.

• In a small, heat-safe bowl, place the chopped bittersweet chocolate and the butter.
• Melt until smooth by placing in a double boiler or microwaving in 45 second intervals at 60% power, stirring in between intervals.
• Set the melted chocolate mixture aside to cool briefly.

Make the cookie dough.

• In a large bowl, place the flour, xanthan gum, cocoa powder, salt, baking soda, and granulated sugar, and whisk to combine well.
• Add the brown sugar, and mix to combine, working out any lumps.
• Add the melted and cooled chocolate and butter, plus the eggs and vanilla, and mix to combine.
• Add the chocolate chips to the cookie dough, and mix until they're evenly distributed throughout it. The cookie dough should be thick but should come together fully.
• For thicker cookies, let the cookie dough rest in the bowl for 15 to 20 minutes. It should become easier to handle then, too.

Shape the cookie dough.

• Using a medium-size spring-loaded ice cream scoop or 2 spoons, scoop the cookie dough into portions about 1 1/2 tablespoons each.
• With clean hands, shape each piece of dough into a ball between your two palms. Place the rounds of cookie dough about 2 inches apart on the prepared baking sheet.

Bake the cookies.

• Place the baking sheet in the center of the preheated oven. Bake for 12 minutes, or until the cookies are just set in the center (they will no longer be shiny).
• Remove the baking sheet from the oven a final time, and allow the cookies to cool on the baking sheet for 5 minutes. Don't handle them while they're hot because they're fragile.
• Transfer the cookies to a wire rack to cool completely.