Remove stems from portabella mushroom caps and wipe with a damp paper towel to remove any dirt or debris.

In a small saucepan, heat 1 tbsp olive oil over medium heat.

Add mushroom caps and cook for 2 minutes on each side, allowing mushrooms to cook through but retain firmness.

-Remove mushrooms from pan and place on paper towels to allow liquid to drain off.

-Divide the ground beef into 12 portions, rolling each into a small disc shape.

Add salt and pepper to taste.

In a large grill pan, heat remaining tbsp olive oil over medium heat.

Once the pan is hot, add the meat and allow to cook for 3 minutes on one side.

Flip and allow to cook for 3 minutes on the other side.

Cook to desired level of doneness (I like burgers cooked to medium).

-Stack a mushroom, burger, cheese, onion, pickles and your choice of condiments.

Top with second mushroom cap and add a basil leaf for garnish.

Use a toothpick to hold.