question :)

hello, I have to make a recipe for my speech class, in the conclusion after I did the recipe I want to say: *As you have seen, it was extremely quickly and easy to make.* or *As you could have seen, it was extremely quickly and easy to make,* or *As you could see, it was extremely quickly and easy to make.*
which sentence is ok? and if you have another one that sounds better let me know ...thanks