Mushroom & Swiss Cheese Burgers With Truffle Mayo

• 4 St Pierre Brioche Burger Buns
• 550g beef mince
• Pinch sea salt and black pepper
• Several sprigs fresh thyme, leaves only
• 3 tbsp light mayonnaise
• 1 clove garlic, crushed
• Drizzle truffle oil
• 1 small onion, peeled and sliced thinly
• 2 tsp olive oil
• 1 tbsp butter
• 100g chestnut mushrooms, sliced
• 120g grated Swiss cheese such as Emmental or Gruyere
• 50g baby spinach leaves
• Gem or romaine lettuce leaves,
• 2 vine tomatoes, thinly sliced

1. Make the burgers – put the minced beef into a bowl and season well salt and pepper then add some of the thyme leaves
2. Using clean hands, mix everything together then divide the mix into 4
3. Shape into patties, each slightly wider than the buns (as the burgers will shrink slightly when they cook) and place on a large plate. Cover and put into the fridge while you prepare everything else
4. Mix the mayonnaise, a pinch of black pepper and half of the crushed garlic (keep the rest to one side) together in a small bowl then drizzle in a little truffle oil to taste – you’ll only need a small amount
5. Heat the oil in a frying pan and gently fry the onions with a pinch of salt for 20 minutes
6. Meanwhile, in a separate pan, fry the mushrooms in the butter for about 5 minutes then stir in the rest of the thyme leaves. Lift out and keep warm
7. Add the burgers to the pan that the mushrooms were in and cook for about 5 minutes on each side, pressing them down slightly as they cook to keep their shape. Check they’re cooked all the way through then sprinkle over a little of the cheese
8. Lift out onto a plate. Add the spinach to the pan and allow to wilt for a minute with the heat on minimum (or even turned off)
9. Lightly toast the burger buns if you like then spread a little truffle mayo over each of the bases
10. Add some lettuce and tomato then the burgers with melting cheese
11. Divide the mushrooms and onions between the burgers then sprinkle over the rest of the cheese
12. Finally add some wilted spinach and pop on the lids

Bon appétit!