Preheat oven to 375 degrees F. Line a baking sheet with parchment paper.
Measure the flour carefully. Pour a little over a cup in a bowl and stir it around. Now spoon it into the measuring cup and tablespoons. If you have a scale, it should weigh about 4.7 ounces.
In a small bowl, combine the flour, baking powder, baking soda, salt, and xanthan gum. Set aside.
In a mixing bowl, beat together softened butter and both sugars. Beat in vanilla, then add the egg and beat just until blended. Add the flour mixture and stir. Add the chocolate chips and stir until blended.
Scoop cookies up by tablespoons measures (slightly rounded) or rounded teaspoons and arrange on a parchment lined baking sheet. Bake cookies for about 10 minutes or until they appear set. Let cool on baking sheet for 5 minutes, then transfer to a wire rack.
The yield is approximate. You can make 14 larger cookies or use smaller balls of dough and make up to 20. Keep a close eye on them as they bake because the edges brown rapidly.