Heat 1 tablespoon of olive oil in a large skillet over medium heat.
Add mushrooms, thyme and parsley; sauté for 10 to 15 minutes or until mushrooms are tender.
Remove from skillet and set aside.
Form ground beef into patties then season each side with salt, pepper and garlic powder.
In the same skillet, heat remaining tablespoon of olive oil over medium heat.
Add beef patties; sauté for 4 to 6 minutes per side or until they reach desired level of doneness.
Remove them from the skillet and allow them to rest for 1 minute.
To serve, layer as follows: a tomato slice, a beef patty, mushrooms and sliced avocado.