In a bowl of your stand mixer, mix both types of flour, salt and fast-action yeast.
Pour the milk into a small saucepan, add the sugar and butter and heat on low stirring just until the sugar has dissolved and the butter has melted. Leave to cool down to lukewarm.
Add the milk to the flour mixture and, using a dough hook attachment mix in your stand mixer for about 7-8 minutes.
Shape a ball and place it into a lightly greased bowl, cover and leave for a couple of hours in a warm spot (or until doubled in size).
Using a pastry brush, grease a 2lbs (900ml) loaf tin with some odourless oil. Lightly dust it with flour.
Tip the dough onto a lightly floured surface and divide the dough into three equal-sized pieces. Shape three balls and place them in the tin snuggly. Dust the top with some flour, cover with a tea towel and leave for 1 hour in a warm spot (or until doubles in size again).
Preheat the oven to 220°C. Using a sharp knife or a dough scorer, slash the dough 3-4 times and place the tin in the middle of the oven for 10 minutes. After 10 minutes, without opening the oven, reduce the heat to 170°C and continue baking for another 30 minutes.
Once baked, leave in the tin to cool for 5 minutes, then transfer onto a cooling rack to cool completely before slicing.