Take a bowl, add curd, sugar, oil and milk. Make sure curd and milk should be at room temperature.
Whisk it to mix everything well. Not necessary that sugar should be dissolved.
Now add caramel sauce and whisk very well so that it emerges finely. Place a sieve on the bowl and sift all purpose flour, baking powder, baking soda & salt in it.
Add butterscotch essence. In case of non availability, you can add vanilla essence.
Mix it. Make sure it should be lump free. And also don't overdo.
Transfer the batter to the greased oil tin and tap it so that air releases, if any.
Bake in a preheated oven @180°C for 40 - 45 minutes.Then check it by inserting tooth pick , if it comes out clean your cake is properly baked.
Take it out of oven and let it cool on cooling rack.
Invert and enjoy by cutting into slices.