Pitched roof on garage - puddle formation

Hello! I have a garage built in 1965 on a garage yard. Unfortunately, water runs into the garage through the pitched roof. A large puddle forms at one spot on the garage. Before I apply a new welding membrane, I want to somehow even out this depression. The depression is about 2 cm deep at its lowest point. Do you have any ideas?

Regards, padrinoxy

There are aggregates where the "grains" are coated with bitumen. These are intended for flat roof profiling and are probably exactly what you are looking for. These aggregates need to be compacted and then retain their shape.