1 pound ground beef
1 tablespoon Worcestershire sauce
1/2 teaspoon garlic powder
1/4 teaspoon kosher salt
1/8 teaspoon ground black pepper
4 large portobello mushrooms, stem removed
4 slices American cheese
1 avocado, thinly sliced
Shredded lettuce
Preheat the oven to 350 degrees F.
In a medium-sized bowl, combine the ground beef, Worcestershire, garlic powder, salt, and pepper. Mix well with your hands until the mixture is well combined.
Remove the stems from the portobellos and place them stem-side up on a parchment-lined baking sheet.
Form the meat mixture into four patties. Press down in the middle of the patty to make a small indent.
Place the burger patties on the portobello mushrooms and bake for 25 minutes.
Add the American cheese and bake for an additional 5 minutes.
Garnish each burger with a few avocado slices and shredded lettuce.