Spray a 2-cup ramekin with nonstick cooking spray. Place pineapple slice, brown sugar, and cherry or raisins in the bottom of the prepared ramekin. Set aside.
In small bowl or cup, briefly beat egg until almost uniform in color. Add remaining ingredients and mix well to combine.
Pour batter over prepared base and tap ramekin to level batter. Microwave on high for 2 minutes.
Cake will rise and then settle a little during baking.