Preheat the oven to 325°F. Grease an 8" pan with butter. Combine the butter and the chocolate chips in a large glass bowl and microwave on high, 30 seconds at a time, until the butter has melted and the chocolate dissolves when you stir it. It should only take a minute or so. (This can be done in a saucepan on the stove.)
Add the brown sugar, vanilla and spices and stir to combine. Taste the mixture and adjust the chile to taste. It should leave just a hint of heat in your mouth. (or a whole lot of heat, if that's more your style.) Stir in the eggs and then the brown rice flour, tapioca starch and salt.
Pour into the prepared pan and bake for 28 minutes, just until an inserted toothpick shows moist crumbs. Let the bars cool before slicing. (Or slice them warm with a plastic knife for clean edges.) Enjoy!