Start by cooking the burgers according to the package directions. Remove the burgers and set aside.
In the same hot skillet add the oil and onions. Saute about 6 minutes or until the onions are translucent. Then add the mushrooms, salt, pepper, and granulated garlic.
Continue to saute for about 4-5 minutes or until the mushrooms are fully cooked.
Build the burger by adding the meat to the bun and the mushroom/onion mixture on top. Enjoy!