Preheat oven to 350oF (180oC).
Grease sides and bottom of round cake pan (7 inch, 18 cm diameter). Line bottom of pan with parchment paper. Set aside.
To a bowl, add sugar and water. Mix until sugar dissolves completely.
Then, add oil and mix well.
Sift in flour, cocoa powder, baking powder and baking soda.
Mix until dry flour is no longer visible. DO NOT OVER MIX (mix until dry and wet ingredients are just combined).
Transfer batter to prepared cake pan. Spread batter evenly.
Top cake with sliced pear and sprinkle with sugar.
Bake in preheated oven at 350oF (180oC) for 45-50 minutes , or until toothpick inserted in the middle of cake comes out clean.
Let cake cool down for 5-10 minutes in pan. Then, transfer to wire rack to cool down completely.