Soft chocolate cake without eggs, without oven and mixer

Ingredients:

120g All purpose flour
25g Cocoa powder
1/2 Tsp Baking powder
1/4 Tsp Baking soda
1/2 Tsp Vanilla powder
125g Sugar
220 ml Milk
50 ml Cooking oil
1/2 Tsp Lemon juice

Ganache chocolate
150g Dark chocolate
60g Milk
1/2 Tsp Butter