Preheat oven to 350 degrees and grease an 8×8x2 pan (or a 9 x 12 pan if doubling recipe) or 12 muffin tins. (You can line the pan with parchment paper so that you can easily lift out the brownies and slice them when they are done.).
Melt butter in a sauce pan or in a 1 quart container in the microwave. Remove from heat. Add cocoa until blended, then add sugar and mix well. Add eggs, one at a time. Stir in vanilla, flour, salt & xanthan gum – do not overmix.