Spray a lite coating of nonstick cooking spray in the mini cast iron skillets.
In a large bowl, follow the package directions for making the brownies. Start with the wet ingredients first by combining the egg, oil, and water.
Then add the package of dry ingredients and mix the batter really well.
Pour the batter into the skillets and place in the Traeger directly on the grill grate.
Cook the brownies for 30-35 minutes with the lid closed. To check for doneness, poke a toothpick in the middle of the brownies. If the toothpick comes out clean, the brownies are done.