Same procedure as the white bread recipe, but use 50:50 white:wholemeal flour. I’d be inclined to add about 5 – 10g of sugar. Something interesting, like Muscovado would be good, but caster sugar is fine. Treacle, Golden Syrup, molasses and honey are all acceptable alternatives.
The resulting dough, below, looks quite white.
But goes a reassuring shade of brown, once done. Note that it doesn’t rise as much as a white loaf.