Method
1. Add potato to a clean saucepan
2. Boil until soft - 15 min
3. Drain with sieve
4. Mash with potato masher then set aside
5. Add water, active dried yeast and honey to a clean large mixing bowl
6. Whisk briefly until combined
7. Let rest - 10 min
8. Transfer vegetables to dough
9. Add unsalted butter, egg and salt to the dough
10. Mix until well combined
11. Add whole wheat flour and all purpose flour to the dough
12. Mix until well combined
13. Knead until elastic - 10 min, dough hook
14. Grease a clean large mixing bowl
15. Transfer dough to large mixing bowl and cover
16. Let rise - 2 hr
17. Grease a clean round pan
18. Turn out large mixing bowl on lightly-floured surface
19. Form
20. Transfer content of large mixing bowl to round pan and cover
21. Let rise until doubled - 1 hr
22. Pre-heat oven - 190°C
23. Bake until golden brown - 25 min, 190°C
24. Serve