Place coconut and almond milk, xanthan gum, cocoa powder, vanilla, and sugar in a blender and blend until well combined. Transfer to a mixing bowl, cover and refrigerate until chilled through - at least a couple hours.
Once chilled, pour into pre-chilled ice cream maker and use according to directions. (Alternatively, pour into a freezer-safe container, cover and freeze, taking out to stir every couple hours to aerate.)
Once the ice cream is at soft-serve consistency, add in brownie chunks. You can either do this at the end of the ice cream maker's churning process, or once you pour it into a container. Smooth the top with a spoon, cover, and freeze until firm. Or eat immediately though it will be quite soft.