1. Grill the Burgers

Preheat barbecue to medium-high heat. Lightly brush grill grates with oil. Place frozen chicken burgers on the grill and cook for 9–10 minutes, turning frequently, until cooked through.

2. Caramelize the Onions

Slice onions thinly. In a pan over medium heat, cook onions slowly with a little oil or butter, stirring occasionally, until they are soft and golden brown (about 10 minutes).

3. Cook the Mushrooms

Slice mushrooms and sauté in a pan with a little oil over medium heat until tender and lightly browned.

4. To Assemble

• Place the bottom bun.
• Add lettuce leaves.
• Add the grilled chicken burger.
• Spread ketchup or mayonnaise, as desired.
• Add a slice of marble cheese.
• Top with sliced fresh jalapeños.
• Add a generous portion of caramelized onions.
• Add the sautéed mushrooms.
• Finish with the top bun.