01 -
Combine plain flour, diced cold butter, and salt in a mixing bowl. Rub together with fingertips until the mixture resembles breadcrumbs. Alternatively, briefly pulse in a food processor. Incorporate the whole egg and one egg yolk, mixing to form a soft dough. Shape into a ball, flatten into a disc, wrap, and chill for 30 minutes.
02 -
Lightly dust a work surface with flour. Roll out the chilled pastry to a 4-5 mm thick circle, slightly larger than the intended dish or tin. Transfer to a tray, cover, and chill again to allow the pastry to relax.
03 -
Place sliced potatoes in a saucepan, cover with cold water, and add a pinch of salt. Bring to a boil over medium heat, then reduce to a gentle simmer. Cook for 5-8 minutes until just tender but still holding their shape. Drain thoroughly and allow to steam dry in a colander.
04 -
Heat vegetable oil over low heat in a frying pan. Add shallots and garlic; cook for 8-10 minutes until translucent. Add cubed Tunworth cheese and salt, cooking gently for a further 10 minutes and stirring regularly until the cheese is completely melted.
05 -
In a separate saucepan, gently heat the whole milk, whipping cream, and chopped thyme until just simmering. Pour this hot mixture over the melted cheese and shallots, stirring until fully combined into a rich, smooth sauce. If needed, simmer an additional 2-3 minutes to thicken.
06 -
Preheat oven to 170°C (fan)/Gas mark 5. In a 20-24 cm pie dish or tart tin, arrange a layer of cooked potato slices and season lightly. Spoon over a generous quantity of the cheese sauce. Repeat layering until all potatoes and sauce are used. Brush the rim of the dish with some of the remaining egg yolk.
07 -
Remove the rolled pastry from the refrigerator and lay over the filled dish, allowing a slight overhang. Trim and neaten the edges if needed. Brush the top with remaining egg yolk and scatter with picked thyme leaves.
08 -
Bake for 30-35 minutes until the pastry is golden brown. Remove from the oven, finish with a sprinkle of sea salt flakes, and serve immediately alongside a crisp green salad.