Makes 2 sandwiches

Start by making the balsamic onions: Peel and slice the onions. Melt the butter in a frying pan and fry the onions with a pinch of salt over a medium heat for about 10 minutes, stirring regularly, until they’re really soft.

Add the red wine and cook until absorbed.

Add the cassonnade and the balsamic vinegar and simmer for another couple of minutes until the onions are sticky and the liquid absorbed. Set the onions aside.

Layout the bread slices. Spread some mustard over 2 slices, and some balsamic onions over the other 2 slices. Distribute 60g of mozzarella over two slices and 100g of cheddar over the other two slices. Season with salt and pepper, and put one of each over each other to make a sandwich.

Spread some butter over the top of the two sandwiches. Heat a large frying pan and put both sandwiches, butter side down in the pan. Put a heavy saucepan or a plate with cans on top of the bread slices to weigh down the sandwiches. Fry on a low heat for about 5 minutes.

Once the bottom is nicely browned, remove the weight from the top and spread some butter over the unbuttered sandwich side. Turn the sandwiches over, weigh down again and fry for another 5 minutes or until the cheese is melted.

Once the cheese has melted inside, put the sandwiches on a plate and put the remaining cheese in the frying pan and melt. Sit the sandwiches on the melted cheese in the pan and fry for another moment until the cheese is grilled and crispy. Put on a plate and eat immediately.

Serve with a green salad for some good conscience…

Alternative fillings:
– balsamic onions + blue cheese + ruccola
– ham + cheese + mustard
– cheddar + mango chutney + coriander
– raclette cheese + gherkins + smoked ham