Garlic-Thyme Chicken Smash Burgers with Mushrooms

Steps

1. Prepare everything first: slice the mushrooms and onion, slice the mozzarella, separate the romaine leaves, and gently roll the ground chicken into 8 loose balls without packing them. Keep the chicken chilled until cooking.
2. In a small bowl, stir together the garlic powder, dried thyme, black pepper and half of the salt; set this patty seasoning aside.
3. Heat half of the olive oil in a large cast-iron skillet over medium heat. Add the onion and the remaining half of the salt and cook, stirring often, for 8 minutes until soft and golden.
4. Add the mushrooms to the onion and cook 6 to 8 minutes until browned and their liquid has cooked off.
5. Pour the Worcestershire sauce over the mushrooms and onion, stir to coat, and cook 1 minute more. Move the mixture to a bowl and cover to keep warm. Wipe out the skillet.
6. Toast the whole-wheat bread slices in the dry skillet over medium heat, about 1 minute per side, and set aside.
7. Raise the heat to medium-high and add the remaining half of the olive oil. Place 4 chicken balls in the skillet, cover each with a square of parchment, and smash firmly with a sturdy spatula into thin patties. Remove the parchment and sprinkle the tops with half of the patty seasoning.
8. Cook 3 minutes until the edges are deeply browned and crisp, flip, top 2 of the patties with half of the mozzarella, and cook 2 to 3 minutes more until the chicken reaches 165°F (74°C) and the cheese melts. Stack each plain patty onto a cheesy one.
9. Repeat with the remaining 4 chicken balls, the remaining half of the patty seasoning and the remaining half of the mozzarella.
10. Build each burger on a slice of toasted whole-wheat bread: romaine leaves, a double patty stack, a spoonful of the mushroom-onion mixture, and a second slice of toast on top. Serve right away.