Preheat your oven to 180℃ (350℉).

On a floured surface, roll out the puff pastry until it's about 3mm (1/4 inch) thick.

Use a 24cm (9.5-inch) plate as a guide to cut the pastry into a perfect circle.

Brush off any excess flour and lay the pastry round on the plate or baking tray.

Refrigerate it until you’re ready to use it.

In a 23cm (9-inch) ovenproof heavy-based frying pan, add the sugar.

Place it over medium heat and, without stirring, allow the sugar to melt until it’s liquefied and turns into a rich caramel color.

Swirl the pan occasionally to ensure all the sugar dissolves.

Once it reaches a golden hue, remove it from the heat and whisk in the unsalted butter until fully combined.

Add the vanilla bean paste, stirring well to incorporate all those lovely flavors.

Peel, halve, and core the Granny Smith apples.

Arrange the apple halves in the caramel, placing the rounded side down and the core side facing up.

Pack them snugly in the pan, then return it to medium heat on the stovetop.

Cook the caramel and apples for about 10-15 minutes until the caramel turns a luscious deep golden brown, and the apples start to soften.

Remove the puff pastry from the fridge and gently lay it over the apples.

Using a spoon, carefully tuck the edges of the pastry between the pan and the apples—be cautious, as the pan will be hot!

Prick a few holes in the pastry to allow steam to escape during baking.

Place the pan onto a baking tray and position it on the middle shelf of your preheated oven.

Bake for around 30-35 minutes, or until the pastry is a beautiful golden brown and crisp.

After baking, transfer the pan to a wire rack and let it cool for 20 minutes.

Run a knife around the edge of the tart, place an inverted plate over the pan, and flip the tart over.