My daughter got me this burger stuffer for my birthday. Tried it out and it worked pretty good. Used 1 lb of ground beef for two stuffed burgers. One was stuffed with onions, mozzarella cheese and mushrooms. The other with onions, pickles, cheddar and mushrooms.
I took my one lb of beef and broke it into 1/4 lb balls. Placed one in the stuffer and close and press. Then you turn the top to release the center, push down again and you now have a pocket to place your stuffings.
Now capped with other pattie.
Burger two complete
After grilling using sear and hold method
Internal pics not so good but here they are cut open
The burgers were very good. The sutffings stayed inside. You had to seal up the edges good, but overall, I'd call it worthwile. There is a learning curve, but once you get the hang of it, it works well. By the way, it is called "STUFZ".
Thanks for looking.