Preheat your oven to 350°F. Grease a 10-inch cast iron (or other oven-safe) skillet and set it aside. Alternatively, you can use multiple 6-inch cast iron skillets, and bake the brownies a bit longer.

In a small bowl, place the chopped chocolate and butter. Melt them either in the microwave in 30-second bursts or placed over a small pot of simmering water (making sure the bowl doesn’t touch the water, and the water doesn’t boil), stirring periodically until smooth. Set the bowl aside to cool briefly, until no longer hot to the touch.

In a large bowl, place the flour blend, xanthan gum, cocoa powder, and salt, and whisk to combine well. Add the brown sugar, and mix, working to break up any lumps in the brown sugar. Create a well in the center of the dry ingredients, and add the chocolate and butter mixture, then the oil, vanilla, and eggs, and mix to combine. The batter will be thick but smooth.

Scrape the batter into the prepared skillet or skillets and spread into an even layer with an offset spatula or small knife. Place the skillet(s) in the center of the preheated oven and bake for about 20 minutes (about 25 minutes if you’ve used smaller skillet(s) or a non-cast iron skillet) or until the brownies are just set in the center. Allow to cool for about 10 minutes before slicing into wedges or serving. Or serve immediately by scooping out with a large spoon. But if you do it that way, you have to serve it with a scoop of ice cream or what’s the point.