Made these last night and was happy with the result. I used a 9" diameter round plastic microwaveable cake pan, sprayed w/ cooking spray.
Mix 1 C sugar, 1/2 C flour, 1/3 C cocoa powder, 1/4 tsp salt, 1/4 tsp baking powder, 2 eggs, 1/2 C oil, 1 tsp vanilla. Stir until combined and spread in the microwave pan (sprayed w/ cooking spray.) I microwaved 2 minutes on high, tested, then microwaved 2 more minutes. Then let them set and cool. These are the dense chewy kind.