Start off by preheating the loco cookers griddle to 350 degrees.
Let’s slice up the onions as thin as possible and the mushrooms. Now add about 1 tbsp of cooking oil to the griddle and sauté the mushrooms and onions until tender.
Remove them and now make 4 equal size meatballs with the 1Lb ground chuck, about 4 oz meatballs.
Turn your griddle on sear mode. Now lay down the meatballs on the griddle and use 2 spatulas to smash them as thin as possible. Season those up with salt and pepper.
Once you see the top of the burgers watery, it’s time to flip them. Once you flip them, season once more with salt and pepper.
After 1 minute, top the burgers with mushrooms and onions, then add a slice of Swiss cheese.
After 1 minute, top the burgers with mushrooms and onions. Add a slice of Swiss cheese, let it melt and now it’s time to assemble. On a toasted pretzel bun add your burger, crown with the top bun.