Uniform smooth layers between parts - Tutorial

I've been looking for a long time how to prevent Bambu Studio slicer from drawing the upper solid part shape on the previous under layers.You will find the solution and an exemple in the model of the 2 methods compared. The goal is to get uniform smooth layers of top surface underneath an other part. (I mean fill the top surface at once the same way as if there was nothing else above). This is more for aesthetic purpose but it can also really save time depending the case.I don’t know why it seems not really supported by the slicer. In some specific cases, with complex shapes, the results can be a top surface with a lot of straight lines because of how the printer filled the top surface, by going « around » the future shape of the part that will come – after - in the printing job. I’ve tried adding a layer modificator, with 100% infill. Yes, the slicer, makes 100% infill, but keeps drawing the shape from above, resulting in the same problem. I’ve found a trick and I wanted to share