Preheat the oven to 400 degrees.

Chop the mushrooms and onions.

In a medium skillet, cook the mushrooms, onions, and garlic powder over medium heat for 5-7 minutes, until mushrooms and a bit tender and fragrant.

Cut each puff pastry sheet into thirds, then into thirds again to make 9 squares out of each sheet.

Grease a muffin pan and place a puff pastry square into each of the cavities, and gently press to the bottom and up the sides.

Sprinkle a little cheese into the bottom of each, then add some mushroom mixture and top with more cheese.

Transfer to the oven and bake for 15 minutes, until golden.