To make the crust, rub the butter with the sifted flour using your fingertips until it resembles breadcrumbs.
Add the egg yolk, sugar and 1-2 tablespoons of cold water and mix together to form a dough that does not stick to your hands.
Cover with clingfilm and refrigerate for about 30 minutes.
Roll the dough into a ½ cm thickness (¼ inch), then carefully transfer it to a pie or quiche dish, removing the excess dough around the edges.
To make the filling, add the sweetened condensed milk, canned pumpkin, pumpkin pie spice and eggs to a bowl, and use a hand mixer to beat everything well until smooth.
Scatter the semolina over the crust.
Pour over the filling into the pie dish, and bake in the preheated oven at 200 degrees Celsius (390 Fahrenheit) for 15 minutes, then decrease the temperature to 180 degrees Celsius (350 Fahrenheit) for 40-45 minutes until set, and a skewer inserted into the middle of the filling comes out clean.
Leave to cool, then beat the whipped cream until it forms stiff peaks, add it to a piping bag fitted with a star nozzle, and decorate the pie as you wish.