Cheese and onion toastie recipe

Cheese and Onion Toastie | A crispy grilled cheese sandwich stuffed with cheddar cheese and herby caramelized onions sweetened with balsamic vinegar. It’s the perfect comfort food for lunch, dinner, or snack.

A sliced grilled cheese on a white plate.

If you love grilled cheese sandwiches, you’ll love this onion grilled cheese, also known as a cheese and onion toastie. It’s made by caramelizing onions with balsamic vinegar and thyme and stuffing them with cheese between bread slices.

Classic grilled cheese is great, but sometimes adding a twist leads to more flavour, and better texture. This recipe elevates the traditional grilled cheese into an ultra comforting, and super flavourful lunch idea.

Fry the grilled cheese using a frying pan, for a few minutes on each side until it’s golden and crispy. You can also make grilled cheese in the air fryer.

How to make a cheese toastie

A cheesy toastie is a delightfully crisp sandwich, filled with melty cheese. In this recipe, I’ve added herby caramelized onions for extra flavour.

First, caramelize the onions. Then butter the bread for the outside of the sandwich. Add the cheese and onions to one side and close it up.

Transfer the cheese and onion sandwich to a pan over medium-low heat, and toast until golden and crispy.

A sliced grilled cheese stacked on a grilled cheese on a white plate.

What is a cheese toastie?

Even if you’ve never heard of a cheese toastie, I guarantee you know what it is. A cheese toastie is simply a toasted cheese sandwich. In North America, we call it a grilled cheese sandwich, but across the ocean in the UK, it’s called a cheese toastie.

This cheese and onion toastie consists of shredded cheese and sweet caramelized onions stuffed between slices of bread, buttered, and fried until golden and crispy.

How to make the perfect cheese toastie

There are many ways to make a cheese toastie, with each sandwich lover insisting that their way is the best. The truth is, grilled cheese is hard to mess up. It’s simple, perfect, and easy to make. Here are a few tips that I’ve found to make the best grilled cheese.

Use fresh bread to ensure that the outside gets golden and crispy, while the inside remains soft and fluffy.

Load up on different kinds of cheese. In this recipe, I use a simple sharp cheddar, but using multiple kinds of cheese, like in my bagel grilled cheese, provides bold flavour.

Fry the grilled cheese over medium-low heat. Cheese toasties require low and slow frying. If the heat is too high, the bread will burn in the center instead of evenly toasting.

Ingredients

More about the ingredients in this recipe. The exact measurements are below.

White bread- I like to use crusty white bread for grilled cheese. You can use any type.
Cheddar cheese- Old cheddar is my go to for its flavour. Almost any semi hard cheese will work. Try mozzarella, harvarti, or gouda.
Butter- Use butter or margarine to spread on the bread.
Yellow onion- It has a slight sweetness, making it perfect for caramelizing.
Balsamic vinegar- It adds a slightly sweet tartness.
Thyme- Pairs well with balsamic vinegar and adds an herby flavour.
Salt and pepper to taste

Substitutions

You can use any kind of bread! Check out my bagel grilled cheese.
Instead of thyme, you can use another herb like rosemary or sage, or leave it out.
Any semi hard cheese will work. Or add a soft cheese, like in my goat cheese grilled cheese.

Instructions

If using dried thyme, use half of the amount called for in the recipe card. Dried herbs hold more flavour.

Melt 1 tablespoon of butter in a pan over medium heat and add the onions. Sautee the onions until they become transparent, and start to brown on the edges.

Lightly fried onions in a frying pan with a drizzle of water.

Allow the onions to cook undisturbed for 2-3 minutes until they brown on the bottom of the pan, then add a splash of water.

Deglaze the pan with a splash of water, scraping the onions and the browned bits from the pan. Repeat for about 10 minutes, until the onions are caramel brown colour.

Caramelized onions on a slice of bread on a wooden cutting board.

Add the salt, pepper, thyme, and balsamic vinegar, then remove from the pan. Spread the bread with the remaining butter, and place them butter side down on a cutting board. Add the onions on top.

Caramelized onions and shredded cheddar cheese on a slice of bread.

Add the cheese on top.

An untoasted cheese and onion toastie on a wooden cutting board.

Top with the bread, butter sides facing upward.

A cheese and onion toastie being cooked in a frying pan.

Transfer the sandwich to your hot pan, and cook for 2-3 minutes, until it is golden brown, and then flip.

A toasted cheese and onion toastie in a frying pan.

Cook for 2-3 minutes until the bread is golden brown and crispy, and the cheese is melty.

Slice in half and enjoy.

Tips for making caramelized onion grilled cheese

Deglaze the onions when they start to brown against the pan. This will ensure that they’re flavourful and nicely coloured.
Cook the grilled cheese low and slow to ensure even crispiness. Keep the heat at medium-low.
Don’t skip the balsamic vinegar and thyme! They add great flavour to the onions.

What to serve with grilled cheese

Grilled cheese and soup are a classic pairing. Try my carrot and lentil soup or my lima bean soup.

To balance the grilled cheese sandwich, pair it with a salad or carrot fries.

For similar sandwich recipes, try my bagel grilled cheese or my goat cheese grilled cheese.

Storage

Grilled cheese is best served immediately after making, but it can be stored in the fridge for up to 3 days. Reheat it in the oven at 350°F/180°C for 5-10 minutes, or until heated through.

FAQ’s

How do you make crispy grilled cheese?

To make crispy grilled cheese, fry it over medium-low heat. If the heat is too high, it will burn instead of toasting evenly.

What’s the difference between a grilled cheese and a cheese toastie?

Grilled cheese and cheese toasties are the same thing, they’re just called grilled cheese in North America, and cheese toasties in the UK.