Heat olive oil in a frypan over medium heat. Cook diced onion and crushed garlic for 3-4 minutes until soft.

Add beef mince and cook, stirring constantly, until well browned.

Add crushed tomatoes along with a tin of water. Season with salt and pepper. Stir and bring to a boil.

Reduce heat and simmer for 30 minutes until the sauce is thick and rich. Set aside to cool.

In a medium saucepan, melt the butter over medium heat.

Whisk in the plain flour and cook for 1 minute.

Gradually whisk in the milk to form a smooth sauce. Bring to a boil, then remove from heat and stir in the grated cheese. Season with salt and pepper. Set aside to cool.

Bring a shallow pan of water to boil and cook lasagne sheets a few at a time for 2 minutes or until just al dente. Remove and drain in a colander.

Grease an 18cm x 25cm baking tin and line it with baking paper, allowing the edges to hang over.

Place a single layer of cooked lasagne sheets at the bottom of the tin, cutting to fit if necessary.

Layer half the cooled meat mixture and half the béchamel sauce over the lasagne sheets.

Top with another layer of lasagne sheets, the remaining meat mixture, and the remaining béchamel sauce. Finish with a last layer of lasagne sheets.

Cover with overhanging baking paper and refrigerate for 2 hours or overnight to completely cool and set.

Preheat the oven to 180°C (350°F). Defrost puff pastry sheets just before use.

Cut each puff pastry sheet in half lengthwise, and cut lasagne into 5cm squares.

Place a square on one end of the pastry sheet and fold over the other end to enclose the lasagne. Press edges to seal and use a fork to pattern the edges.

Repeat with remaining pastry and lasagne squares. Place parcels on a baking tray lined with baking paper.

Brush each parcel liberally with beaten egg. Bake for 18 minutes until puffed and golden.