bring a small saucepan of water to a boil
wash, peel, and chop HALF the potatoes for mashing
add them to the water when they're chopped, and cook until soft for mashing
meanwhile put the flour, salt, sugar, and yeast in the bowl of a stand mixer
when the potatoes are cooked drain into a bowl to retain the cooking water, let it cool
get the potatoes really dry by shaking them in a colander
put them back in the saucepan, add the 3T olive oil, mash until smooth
let them cool until they come down to just warmer than room temperature
then add them to the flour mix
stir with the bread hook to combine, then add just enough cooking water to make a dough--be aware the dough comes together quickly so don't add a LOT of the water
once the dough is formed let the mixer do it's magic for 2 minutes
then remove the hook, cover the bowl, let the dough rise until doubled in size
once it's doubled grease a 9X13 baking sheet, and gently pour the dough out on it
pat it out to roughly the size of the pan, let cover lightly and let it rest-it will expand as it rests, don't knock the air out of it
preheat the oven to 425˚
bring a small pan of water to a boil
wash the remaining potatoes, then peel, and cut in large pieces
parboil in the water until just barely soft
drain and slice
remove the cover on the bread, add slices of the potatoes
brush the whole thing with the extra oil
add extra rosemary as desired
bake 20-25 minutes or until the bread is cooked through and a lovely brown
cool on a baking rack, slice or tear to serve