Blue Cheese Mushroom Burger with Caramelised Red Onions

21 September 2016

Celebrate Summer-time with these amazing and delicious Blue Cheese Mushroom Burgers with Caramelised Red Onions! These burgers are certain to transform your summer BBQ this year. Serve on the side with rocket salad or why not treat yourself with chips or potato wedges.

This delicious recipe and photography was created by The Flexitarian. Check out this page for some amazing vegetarian and vegan recipes.

Serves: 6

Cooking Time: 75 Minutes


  • 300g chestnut mushrooms [10.5 oz]
  • 2 organic eggs
  • 100g breadcrumbs (gluten free if needed) [3 oz]
  • 60g shallots finely sliced [2.1 oz]
  • 2 garlic cloves crushed
  • 4 Tbsp parsley (finely chopped)
  • 175ml marsala wine [6 fl oz / US 3/4 cup]
  • 2 Tbsp olive oil
  • salt & pepper


  • 2 large red onions
  • 1 Tbsp olive oil
  • 1 Tbsp butter
  • 2 Tbsp brown sugar
  • 2 Tbsp balsamic vinegar


  • Buns of your choice
  • Blue cheese (or another cheese of your choice such as cheddar, goat cheese, smoked cheese etc.)
  • Salad leaves, tomatoes, pickles etc.


  1. Wash and clean mushrooms. Mince them very finely.
  2. Heat 2 tablespoons of olive oil in a large frying pan. Add finely sliced shallots and crushed garlic.
  3. Add minced mushrooms. Fry gently for 2 mins.
  4. Add marsala wine and finely chopped parsley.
  5. Cook for 10-12 mins until all liquid has evaporated.
  6. Transfer mushrooms to a bowl. Mix in beaten eggs and breadcrumbs. You can use a bit more breadcrumbs if you feel the mix is too wet. Season to taste.
  7. Set aside in the fridge for 1 hour so the breadcrumbs have time to soak up any extra liquid. The burger mixture can be made up to a day ahead and kept in the fridge in an airtight container.
  9. Make the caramelised onions just before you are ready to cook the burgers
  10. Heat olive oil and butter in a large frying pan. Add sliced onions, sugar and vinegar. Stir a little
  11. Leave to cook for 30-40 mins under gentle heat, stirring every now and then so the onions do not stick to the pan. When done, transfer to a serving bowl.
  13. Remove mushroom mix from the fridge. Mould handfuls of the mince mixture into burger patties. You should have 6.
  14. Heat some olive oil in a large frying pan. Cook the burgers for 10 to 12 minutes until evenly cooked. Turn them once.
  15. Serve with buns, salad, cheese and the caramelised red onions.


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