Preheat the oven to 180°C and butter a 22cm diameter round pie dish, loose bottom is preferable.
In the bowl of an electric mixer fitted with a paddle attachment, add the sugar, butter, and eggs. Beat at medium-high speed until the mixer is light in colour and creamy. This can take 5 minutes.
Sift the flour and salt together in a separate bowl.
At a low speed, add the milk, vanilla, and flour mixture to the egg mixture. Blend until just combined.
Melt the two types of chocolate together over a double boiler or in the microwave. Allow the chocolate to cool slightly before adding it in a steady stream to the egg and flour mixture with the motor running at low speed.
Fold through the chopped walnuts with a wooden spoon.
Pour the mixture into the prepared tin and bake in the preheated oven for about 35 minutes. Allow the fudge pie to cool for about 30 minutes before removing the pie from the tin.
Chocolate Fudge Sauce
In a pot set over medium heat, add the butter and chocolate. Allow the butter and chocolate to melt before adding the sugar and cream.
Stir occasionally until the sugar has melted. Remove the sauce from the heat and stir in the salt and vanilla. Pour the sauce into a glass jug.
To serve, slice the chocolate pie and serve with vanilla ice cream and hot fudge sauce. Enjoy!