How to reach the "topping off" on the church

Need a bit of help here. I need to get the topping off from the church in Sasau monestary, but I can’t figure it out.
There is a board sticking out that looks like you obviously should be able to stand on and reach, but when I try to jump up on it I just clip through and fall to my death.

What else can you use to “reach out and touch” things with?