Sift high protein flour and wholemeal flour onto a piece of greaseproof paper then return husks from the sieve onto the paper. Tip sifted ingredients into the bowl of an electric mixer fitted with a dough hook. Stir in sugar, salt, yeast, milk powder and bread improver. Mix in butter, walnuts and sultanas.
Pour water into the flour mixture then turn on the mixer and process for 5 minutes or until the dough is smooth.
Leave the dough in the bowl to rise, cover with a piece of cling film for 30-35 minutes or until doubled in bulk.
Knock the dough down then turn on the mixer for 1-2 minutes. Mix until dough is smooth again.
Remove dough out onto a lightly floured tabletop. Form dough into a long rectangular loaf to fit the prepared pan. Drop dough carefully into the pan.
Place loaf pan in a large oiled plastic bag. Leave aside to rise for about 50-60 minutes or until it doubled in bulk.
Preheat oven to 180°C, then brush the surface of the loaf lightly with fresh milk. Bake for 30-35 minutes until the loaf is golden and the base sounds hollow when tapped.