Make the shortcrust: mix the flour, 150 g of sugar and a pinch of salt. Add the cold diced butter and rub in with your fingertips. Add the egg and quickly bring together into a ball without overworking. Divide into two pieces (60% and 40%), wrap and chill for 30 minutes.

Make the caramel: heat 250 g of sugar dry in a saucepan over medium heat, without stirring, until you have a light amber caramel. Off the heat, pour in the hot cream little by little, watching out for splashes. Return to low heat and stir until the caramel is smooth.

Add the honey, sea salt, cinnamon and chopped walnuts. Cook for 2 to 3 minutes, stirring, then leave to cool slightly. Preheat the oven to 180 °C (170 °C fan).

Roll out the larger piece of pastry and line a buttered 24 cm deep tin, letting the pastry come right up to the top of the sides. Pour in the warm filling and level it.

Roll the second piece into a 24 cm disc and lay it over the filling. Seal the edges by pressing firmly, prick the lid with a fork at regular intervals and brush with egg yolk.

Bake for 35 to 40 minutes, until golden. Leave to cool completely in the tin, at least 1 hour, before unmoulding. To serve, dust with icing sugar and cut into thin slices.