Looks almost real, right? Kind of making me hungry actually. Here's all the layers individually:
The pattern is from one of the many Japanese craft books from my collection. It's called "Tomoko Fujita Knit Room", ISBN4-86191-201-6.
It took me a long time to do the buns but the other pieces went pretty quickly. Although the pattern in the book had an egg instead of an onion slice (must be how they do burgers up in Japan), so I made an onion up by myself by just doing a standard flat round in the back loop only to get the spiraled ridges. Also I could not for the life of me figure out what the pattern for the patty was. I'm usually pretty good at deciphering these things but it had some kind of loop pattern that I have never seen before and I could not get it to turn out right. So I just did a flat round, did 2 even rows in the back loop, then flipped it over and decreased back to the center to make it thick enough. And the cheese was a knitted square and I just didn't feel like knitting it so I crocheted it instead.