Cut potatoes in half and place in a pot of water, so that there is enough water to cover the potatoes. Bring to a boil and cook for 20 minutes. Let the potatoes cool in the water. Drain, reserving the water if desired. (see note below)
Peel and mash the potatoes. You should have 1 1/2 cups of mashed potatoes.
In a bowl, combine milk, honey and olive oil. Whisk to combine.
Heat 1/4 cup water to 110-115 F. Sprinkle yeast on top. Leave it for 5-10 minutes, until the yeast gets foamy.
In the bowl of an electric mixer, beat potatoes with flour and salt. Add proofed yeast and milk mixture. Using the dough hook attachment, knead for 1 minute until just combined.
Cover with plastic wrap sprayed with non stick spray and a kitchen towel. Leave to rest for 30 minutes.
Add flax seed to the bowl and knead for 7-8 minutes until the dough is very elastic. This dough is very soft and sticky, more of a batter dough.
Transfer dough to a lightly greased bowl. Cover with plastic wrap and a kitchen towel. Leave to rise until doubled in size, about 2-2 1/2 hours.
Pull and stretch the dough a few times, but pulling the dough from underneath and stretching it over the top. Transfer to a loaf pan sprayed with non stick spray. Spread bread dough (batter) in an even layer in the pan. Cover loosely with plastic wrap sprayed with non stick spray. (This is very important so that as the dough rises, it does not stick to the tea towel or wrap. This is a very sticky batter dough.). Leave to rise again for 1 hour.
Preheat oven to 350 F after a 1/2 hour of the bread rising. With a sharp knife, gently make a few cuts in the dough.
Bake for 1 hour, until dough sounds hollow when tapped. Leave to cool before slicing.