Preheat the oven to 375 degrees F. Line two baking sheets with parchment paper and set aside.
Whisk all of the flours, the cocoa powder, baking powder, salt and xanthan gum together in a medium bowl. Set aside.
Put the butter and brown sugar into a large bowl and beat with an electric mixer on medium speed until smooth, about 1 minute. Add the milk, vanilla and eggs and beat until blended. Reduce the speed to low and slowly incorporate the flour mixture until thoroughly combined. Add the chips and stir to combine.
Spoon heaping tablespoons (or smaller scoops) of the dough onto the prepared baking sheets, 1 to 1 1/2 inches apart. Bake the cookies in two batches, two sheets at a time, until the cookies are set and just beginning to crack slightly on top, 13 to 14 minutes. Rotate the sheets halfway through for even baking.
Remove from the oven and let the cookies cool on the sheets for 2 minutes, and then remove to a rack and cool completely.
*available at health food stores Gluten-Free Eggnog Cookies: Make the Gluten-Free Chocolate Cookies, adding 1/4 teaspoon ground nutmeg to the flour mixture. Add 2 tablespoons bourbon whiskey to the butter and sugar. Bake as directed. Gluten-Free Apricot Pistachio Chocolate Cookies: Make the Gluten-Free Chocolate Cookies, folding in 3/4 cup each roughly chopped dried apricot and pistachio nuts. Gluten-Free Lemon and Raisin Cookies: Make the Gluten-Free Chocolate Cookies, adding 1 teaspoon lemon zest to the butter mixture, and substituting 1 cup golden raisins for the semisweet or white chocolate chips.
From Food Network Kitchens