In a small bowl, combine the warm water, milk, yeast and sugar.

In the bowl of a stand mixer (or a large bowl if kneading by hand), combine the flours & salt. Add the butter and rub in with your fingers until the butter is the size of crumbs.

Attach the dough hook. Add the yeast mixture and egg.

Run the mixer of medium for 5-8 minutes, until a soft, smooth, supple dough forms. (if kneading by hand, knead for 8-10 minutes)

Remove the dough from the bowl. Lightly grease the bowl with olive oil and return the dough to the bowl. Cover bowl with a clean, damp tea towel and let rise until it has doubled in size (1-2 hours, depending on room temperature - it took 1.5 hrs for me in a 20°C room).

Line a baking tray with baking paper. Tip out the dough onto a chopping board, and divide with a knife or kitchen scissors into 6 even pieces. (you could also make 8 smaller burgers if desired)

To shape into balls, gently tuck the edges of the dough underneath it. Using a flour-free space on your board, cover the ball with your hand (seam side down), and gently roll in a circular motion into a tight ball (with a floured surface the dough will simply slip around, rather than lightly sticking to form a ball)

Transfer to the baking tray. Cover loosely with plastic wrap and let rise for another hour, or until puffy and slightly risen.

Preheat the oven to 200°C.

Gently brush each bun with milk (to ensure a shiny surface on your finished buns).

Bake for 15-20 minutes or until golden brown. Cool before serving.