Onion and blue cheese tart

Ingredients

• 1small tart pastry case
• 100 gblue cheese (Roquefort)
• 170 gmozzarella
• 100 gdouble cream
• 2onions
• 30 gbutter
• 50 gsugar
• 1 tspsalt
• to tasteblack pepper

Instructions

1. 1

   Slice the onions

   Cut the onions into thin strips, or feather-like slices, so they remain distinct in the finished tart.

2. 2

   Soften the onions

   Melt the butter in a frying pan over a medium heat. Add the onions and season with salt and pepper to taste.

3. 3

   Add the sugar

   When the onions have softened and become slightly translucent, stir in the sugar until it has dissolved completely.

4. 4

   Stir in the cream

   Add the cream and mix it through the onions, then arrange the mozzarella over the top.

5. 5

   Add blue cheese

   Once the mozzarella has melted, turn off the heat and add the blue cheese in pieces.

6. 6

   Fill and bake

   Place the pastry in a dish slightly smaller than its diameter, covering the base and leaving raised edges to hold the filling. Pour in the filling and bake at 220°C for 20 minutes, or until the top is browned.

7. 7

   Cool before serving

   Take the tart out of the oven and leave it to cool for a few minutes so it firms up before you remove it from the dish.

What is an onion and blue cheese tart?

This is a savoury tart built around softened onions, cream and two cheeses: mild, stretchy mozzarella and punchy blue cheese. The recipe does not specify a particular regional origin, but it uses the familiar format of pastry holding a rich, baked filling.

The contrast is what makes this version work: sweetened onions mellow the saltiness of the blue cheese, while mozzarella melts into the creamy mixture.

Nutrition and macros by portion

The nutrition label shows one serving as written: 2100 calories, 70g protein, 150g carbs, 135g fat.

The pastry and sugar contribute most of the carbohydrates, while butter, cream and cheese provide much of the fat; the cheeses also supply the protein. The blue cheese, mozzarella and added salt make this a salty, rich tart, so balance a serving with plenty of salad or vegetables.

Choosing the cheese

Mozzarella: use it for a mild, melting layer that helps bind the filling. The recipe calls for 170 g.

Blue cheese: Roquefort is the named option, added in pieces after the pan comes off the heat. Its stronger flavour carries through the cream and onions.

Getting the onions right

Even slices: cut the onions into thin strips so they soften at a similar pace and keep their shape in the tart.

Gentle cooking: cook them in the butter over a medium heat until slightly translucent before adding the sugar. Stir until the sugar dissolves, rather than letting it sit in a lump.

Making the filling

Cream first: mix the cream into the sweetened onions before adding the mozzarella. This spreads the creamy base through the pan.

Blue cheese last: add it in pieces once the mozzarella has melted and the heat is off. This follows the recipe's sequence and leaves the blue cheese distinct in the filling.

Baking and doneness

The oven should be at 220°C, and the recipe gives a baking time of 20 minutes. Look for a browned, gratinated top as the visual cue that it is ready.

The pastry is placed in a dish slightly smaller than its diameter, leaving raised edges to contain the filling. Take care when adding the filling so it stays within those pastry walls.

Serving the tart

Let the tart stand for a few minutes after baking so the filling firms up and the tart is easier to remove from the dish. Serve warm, when the cheeses are still soft.

A crisp green salad or simply dressed leaves make a fresh counterpoint to the creamy, salty filling. Cut modest slices if serving it as part of a meal with sides.

Recipe notes & tips

• Slice the onions evenly so they soften at roughly the same rate.
• Season the onions with pepper as well as salt while they cook.
• Stir the sugar until no grains remain before adding the cream.
• Turn off the heat before adding the blue cheese.
• Use a dish slightly smaller than the pastry so the edges can rise around the filling.
• Rest the tart for a few minutes before trying to remove it from the dish.

Variations

• Use another blue cheese: Choose a blue cheese with a similar strength if Roquefort is unavailable.
• Add thyme: Stir a little thyme into the onions for a savoury herbal note.
• Include mushrooms: Cook sliced mushrooms until their moisture has evaporated before mixing them into the filling.
• Try a different onion: Use red onions for a slightly sweeter, colourful filling.
• Add walnuts: Scatter chopped walnuts over the top before baking for a crunchy contrast.

Common mistakes to avoid

• Thick onion slices: They may stay firm; cut them into thin, even strips.
• Adding sugar too soon: Wait until the onions are slightly translucent so they have softened first.
• Leaving sugar unmixed: Stir until it dissolves completely before pouring in the cream.
• Overheating the blue cheese: Turn off the heat before adding it, as the method directs.
• Filling a flat pastry base: Leave raised pastry edges so the filling is contained.
• Removing the tart straight away: Let it rest for a few minutes to help it firm up.

How to store

Once cool, cover and refrigerate for up to 3 days. Reheat portions in an oven until hot throughout; the pastry may soften a little after storage.

Frequently asked questions