Onion Tart

This delicious onion tart combines sweet caramelised onions with a flaky, buttery pastry for the perfect savoury treat. Simple yet elegant, it’s ideal for lunch, brunch, or a light dinner paired with a crisp salad. Packed with rich flavour and melt-in-your-mouth texture, it’s a dish that’s sure to impress every time.

Onion Tart – Flaky Pastry with Caramelised Onions & Cheese

There’s something wonderfully comforting about this onion tart. This is a dish that turns the simplest ingredients into something genuinely special. Inspired by the classic French pissaladière, this rustic version skips the anchovies and adds cheese. It celebrates everything that makes home cooking so satisfying: rich flavours, golden pastry, and that irresistible aroma of onions slowly caramelising on the hob.

This dish starts with a light, flaky crust topped with cheese and sweet, caramelised onions, creating a balance of savoury and sweet that’s hard to resist. Black olives add a burst of flavour and contrast, tying everything together. I am using a mixture of yellow and red onions to give this tart an extra depth of flavour.

Serve it warm with a crisp green salad tossed in a simple vinaigrette for an effortless yet elegant meal. Whether you slice it into small slices for a starter or enjoy it as a main, this onion tart is proof that you don’t need complicated ingredients to create something truly satisfying.

🌱 MAKE IT VEGAN : To make this onion tart vegan, simply use dairy-free spread and cheese.

Why you will love this onion tart

• Simple ingredients, big flavour: Just a few everyday staples come together to create something far more than the sum of their parts. Caramelised onions, flaky pastry, gooey cheese, and olives. Every bite delivers comfort and depth.
• Rustic yet elegant: Inspired by the French pissaladière, this tart feels effortlessly chic without being fussy. It’s the kind of dish that looks beautiful on any table, from a casual family meal to a dinner party spread.
• Versatile to serve: Enjoy it warm from the oven with a crisp green salad for a light main, or cut into smaller slices as a delicious appetiser.
• Make-ahead friendly: The caramelised onions can be prepared in advance, making it easy to assemble and bake when you’re ready.
• Comfort in every slice; With its buttery crust, rich onion sweetness, and savoury toppings, this tart hits that perfect spot between indulgent and wholesome.

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Watch how to make this onion tart

How to make this onion tart

Ingredients needed

To make this onion tart, you will need:

• white flour (all purpose or white spelt)
• wholemeal spelt flour
• dry mixed herbs
• salt & pepper
• butter (dairy-free or conventional)
• water
• yellow onion
• red onion
• olive oil
• dark brown sugar
• balsamic vinegar
• grated cheddar-style cheese
• black olives

Step 1: Make the dough

• In a large bowl, stir together the flours, herbs, and salt in a bowl. Using your fingertips, rub the butter into the flour until you have a mixture that resembles sand.
• Adding one tablespoon of ice-cold water at a time, work the dough into a bowl. Knead until you have a smooth dough (you might need to add flour or water). If you are using dairy-free spread or butter, you will require less water for the dough.
• Wrap the dough into cling film or place it in an airtight container and place in the fridge for 30 minutes.

Step 2: Prepare the onions

• In the meantime, cut the onions into thin slices.
• Heat the olive oil in a large frying pan over medium to high heat. Add the onions to the pan, followed by the sugar and vinegar. Stirring frequently, cook the onions until they are soft and caramelised, about 15 to 20 minutes. Add 1 or 2 Tbsp of water if the onion mixture is a bit dry. Season with salt and pepper.

Step 3: Roll out the pastry

• Preheat the oven to 200°C/ 400°F.
• Cut out 2 large pieces of parchment paper and place the dough in the middle of one of them. Place the second piece of parchment paper on top of the dough and roll out the pastry to a round shape of about 28 to 30 cm (11 to 12 inch) diameter and 6mm (¼-inch) thickness. Peel off the top sheet of parchment paper and slide the pastry with the bottom parchment paper on an oven tray or pizza tray.

Step 4: Build the onion tart

• Scatter the grated cheese all over the pastry.
• Leaving a 5 cm (2-inch) edge, arrange the onions on top of the pastry.
• Fold the pastry edge inward to create a border. Trim excess parchment paper from around the onion tart.
• Top with black olives.

Step 5: Bake and serve the onion tart

• Bake in the oven for 30 to 35 minutes until the crust is golden brown.
• Serve hot.

Serving Suggestions and Pairings

Whether as an appetiser or main, this onion tart is a versatile recipe that you can serve as a casual weekday dinner or when entertaining. Pair it with a crispy green salad tossed in a light vinaigrette

Make-Ahead and Storage Instructions

This onion tart can be prepared ahead of time and is best enjoyed straight out of the oven. Leftovers can be enjoyed warm or cold.

Make-Ahead Options

• Pastry Dough: Prepare and refrigerate up to 2 days in advance, or freeze for up to 3 months.
• Caramelized Onions: Cook and refrigerate up to 3 days before assembling the tart.
• Fully Assembled Tart: Prepare the entire tart up to 24 hours in advance, cover tightly, and refrigerate before baking.

Storage and Reheating this Onion Tart

To store leftover onion tart:

1. Allow the tart to cool completely at room temperature.
2. Cover tightly with plastic wrap or aluminum foil.
3. Refrigerate for up to 3-4 days.

To reheat:

• Oven Method (Preferred): Preheat oven to 175°C (350°F). Heat tart for 10-15 minutes or until warmed through.
• Microwave Method: Heat individual slices for 30-60 seconds, though this may slightly soften the crust.

Note: For the best texture, avoid freezing the baked tart, as this can affect the consistency of the filling and crust.

I hope you enjoy this onion tart recipe as much as I do. If you do make it, don’t forget to tag me on Instagram!

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