1Combine flour, sugar and salt in a mixing bowl. Rub in cubed cold butter, add egg and quickly knead into dough. Wrap in foil and let rest in the fridge for 1 hour.
2Grease and flour a 10 inch spring form and press 2/3 of the dough into it, making a rim of 1.5 inches.
Roll the remaining 1/3 of dough into a circle to cover the torte.
3Put the pastry in a cool place.
IN a pot, bring sugar and 3 tbsp. water to a boil. Don't stir, just watch until, on low heat, it has caramelized (light brown). Add cream, slowly boil for 12-15 minutes, then add chopped walnuts, stir well to combine, remove from heat and let cool until it is lukewarm.
4Preheat oven to 200 degrees C (400 F).
Pour filling into pastry, cover with the remaining dough circle (you might have to fold over some of the rim, then press the cover with a fork onto the rim)
5Bake for about 30-35 minutes until golden brown. Let cool for at least 20 minutes before removing the rim of the spring form.