The burger is inspired by the three most popular burgers from Smashburger's menu: the Bacon Stack Smash, the Spicy Jalapeño Smash and the BBQ Bacon Smash.

Preheat the oven to 180C/350F/Gas 4. For the mushroom, cheese and steak stack, drizzle a little olive oil over the Portobello mushrooms. Heat a frying pan over a medium heat and fry the mushrooms ...