For the sour cream shortcrust pastry: place the flour, salt and butter in a food processor and whiz briefly. Add half the sour cream and continue to whiz. You might add a little more sour cream, but not too much as the mixture should be just moist enough to come together. If making by hand, rub the butter into the flour until it resembles coarse breadcrumbs then, using your hands, add just enough sour cream to bring it together.
With your hands, flatten out the ball of dough until it is about 2cm thick, then wrap in cling film or place in a plastic bag and leave in the fridge for at least 30 minutes or, if you are pushed for time, in the freezer for 10–15 minutes.
Preheat the oven to 200ºC 4. For the filling: prepare the apples, by peeling them with a peeler to keep them in a nice rounded shape, then cut into quarters. Remove the core from each quarter and set aside. Don’t worry if they go brown, and don’t cover in water or they will be too wet.
Place the sugar and water in a medium-sized ovenproof saucepan set over a low–medium heat and stir until the sugar dissolves.
Increase the heat and boil the syrup until it starts to caramelise around the edges – about 5 minutes. Do not stir once it has come to the boil otherwise the syrup will crystallise. Once the syrup starts to turn golden, you may need to swirl the pan slightly to even out the caramelisation.
Once the syrup is a golden caramel in colour, add the butter and swirl the pan again to distribute it through the caramel.
Remove the pan from the heat, and place the apple quarters in a concentric circle around the outside and any remaining pieces in the centre, keeping in mind that the tart will be flipped over when serving. The apples must completely cover the base of the pan; you may need an extra apple!
Place the pan back over a medium heat and cook for 10 minutes to slightly caramelise the apples, while you roll out the pastry.
. Roll the pastry out on a lightly floured work surface to a disc about 2cm wider in diameter than the pan. Remove the pan from the heat and place the pastry on top of the almost cooked apples. Using the base of a spoon or a fork, tuck the pastry in around the edges of the apples. Brush the pastry with beaten egg then, using a skewer or fork, prick a few holes in the pastry.
. Bake in the oven for 25 minutes or until the pastry is golden and the apples feel cooked when you insert a skewer through the centre.
. Remove from the oven and allow to stand for just a few minutes before placing a plate on top of the pan and carefully (it is hot!) but quickly flipping it out. Use a plate with a slight lip to catch the delicious juices. Cut into slices to serve. Serve with whipped cream, ice cream or whipped cream with a little icing sugar and cinnamon or Calvados mixed in.
Cook’s tip: try adding 1 teaspoon of ground cinnamon to the pastry. You can also make this with puff or sweet shortcrust pastry. If you wish, use golden caster or granulated sugar, but it is a little trickier to see when it is caramelised, so keep watching the pan. The mixture will go a shade darker than the original golden colour and should take about 5 minutes in total over a medium–high heat. If it burns, we would suggest cutting your losses and starting again!
Adapted from Rachel Allen, Bake (Collins)