Leek and Onion Toasted Cheese Sandwich Inspired by Borough Market, London

Are you in the thick of winter? Cold? Snowy? Chilly? On a day like this a warm grilled cheese sandwich is the perfect anecdote to make us feel all warm and toasty.

About the recipe

This recipe comes to you all the way from London from the Borough Market food stall Kappacasein Dairy. We were in London back in December of 2019 on holiday and stopped by the very popular foody market Borough Market.

Here we saw the most amazing array of food stalls that it was hard to decide what to eat and where to eat, as everything looked so enticing!

Kappacasein Dairy Toasted Cheese Sandwich

One stall however stood out from all the rest. This one had a line snaking all the way around the corner. We were wondering what people were in line for?

While some of us got in line, my daughter and I went to the front of the line to see what this shop was all about.

Imagine our delight to find out it was a grilled cheese sandwich stall! Of course in the UK they call these sandwiches toasted cheese sandwiches.

The sandwich was so popular that even after seeing the long line folks just made it longer.

Three types of cheese for that unique flavor

What makes this grilled cheese sandwich so unique is the mix of cheeses. The sandwich is made with cheddar and two local cheeses known for their creamy, melting texture – Raclette and Ogleshield cheese.

Look at that mound of cheese!

Both these cheeses make the sandwich all gooey and creamy and delicious. Good substitutes for these are gruyere, parmesan, comte, fontina, emmantel, and asiago.

Leeks and onions for extra pizzaz

What also makes this taste phenomenal is the leeks and onions! These give the sandwich an extra boost of flavor that is outstanding.

Farm bread for a wonderful toasty

Of course don’t forget you want to make this sandwich on good hefty country farm bread or a flavorful sourdough.

And now for the recipe inspired by our visit to London in chilly December.

Leek and Onion Toasted Cheese Sandwich.
Aka Grilled Cheese with Leeks and Onions
with inspiration from Borough market Kappacasein Dairy


1 cup sharp Cheddar cheese shredded
1 cup Comte or Raclette cheese shredded
1 cup Ogleshield cheese (a British cheese used for its melting feature)
Cook’s Notes: Use a combination of 1 cup cheddar cheddar plus 2 cups of any of these cheeses – Gruyere cheese, Emmental Cheese, Asiago Cheese, Appenzeller Cheese, or Fontina Cheese.
1 small red onion finely cut
1 small yellow onion finely cut
2 leek stalks tough green parts discarded, tender green parts finely cut.
12 farm bread slices or sourdough bread


In a saute pan melt 2 tbsp butter. Add the leeks and cook until the leeks are shiny and bright in color about 1-2 minutes. Turn the stove off. Transfer leeks to a bowl.

Wait for the leeks to cool then add the chopped onions and mix together. Next add all the cheeses and mix in to make a leek and cheese mixture.

Get ready to make the toasties. Butter slices of bread on one side.Place the butter side down and top with cheese and onion mixture. Sprinkle with salt and black pepper. Cover with another slice of bread with butter side up.

In the same saute pan toast the sandwich on both sides on medium low heat until the bread is golden in color and crisped, and cheese is melted.

Serve right away.

10 thoughts on “Leek and Onion Toasted Cheese Sandwich Inspired by Borough Market, London”

  1. Wow Dolly, what a scrumptious sandwich and i get so much insight from your travels. Having studied in UK never seen Borough market.
    have been reading all your posts, love your salad recipes.
    Look forward to your blogs

  2. Wow, those look spectacular. I’m going in March to visit Alessia. I will go for sure and order one of those. Thanks for the inspiration!! 😋.

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