Peel potatoes and boil until tender.
In a blender add ⅓ of the potatoes and ⅓ of the milk, blend until smooth. Pour into a medium/large pot and continue until all the potatoes and milk are blended.
Add the butter and salt, stir until well combined and heat on medium-low heat until hot.
Whisk together the flour, baking powder, salt, Parmesan cheese and rosemary. Make a well in the middle add the milk and olive oil, stir together.
Move to a lightly floured flat surface and knead until smooth 1-2 minutes. Cover with a clean towel and let rest 20 minutes.
Roll dough very thin and cut into approximate 1 -2 inch squares, using a pizza cutter or pastry wheel makes it easier. Place on the prepared cookie sheets and sprinkle with coarse salt if desired.
Bake for approximately 8-10 minutes or until golden brown. Serve with the soup.