Preheat your oven to 350F and oil a 10-inch, well-seasoned cast iron skillet.
Mix together the flour, coconut sugar, cocoa powder, baking soda, and sea salt in a mixing bowl.
Separately, whisk together the sunbutter, yogurt, and vanilla.
Melt 5 ounces of the non-dairy chocolate chunks or morsels with the coconut oil in the microwave or over a double boiler. (For microwave place in a glass bowl and do 20-30 second bursts stirring in between)
Add a few spoons of the sunbutter/yogurt/vanilla mix to the melted chocolate to temper it. Stir. Add a few more. Stir. Then add the rest and combine well. 6) Combine wet and dry ingredients. The batter will be very thick.
(Optional) Fold in the remaining 3 ounces chocolate chunks or morsels.
Spread the batter into your skillet. Bake for 22 minutes, or until the top is set and the edges firm.
Remove the skillet brownie from the oven and allow it to cool for at least 30 minutes before serving.