Add all ingredients in the order in which they appear to a microwave-safe mug or measuring cup. Stir in the chocolate chips (if adding).
Microwave on high 40 to 60 seconds, until cookie has set up.
Allow cookie to cool for 1 minute before enjoying.
Notes
*I have found various gluten-free flour blends have different absorbencies so the results may vary depending on what brand of GF flour you use. I use Bob's Red Mill Gluten-Free 1-to-1 Baking Flour but have found the recipe results in a greasier cookie when I use Pamela's. For a smaller cookie, make this recipe: