In a large bowl, or the bowl of a stand mixer, combine 4 cups of flour, the mashed potatoes, water, butter, eggs, sugar, yeast and salt. Mix all of the ingredients together, adding up to another half cup of flour if the dough is overly sticky. If using a mixer, change to the dough hook and knead until you have a smooth, soft dough. If making by hand, turn the dough onto a lightly floured surface and knead until the dough is smooth.

Lightly grease a large bowl and add the dough. Cover with plastic wrap or a towel, and let it sit until it has doubled in size, about and hour and a half.

Once the dough has risen, punch it down and divide it into 15 equal portions. Working with one portion of dough at a time, pinch the edges together to form a ball. Place the ball on a counter and cup you hand over it. Work your hand in a circle, gently pushing pressure on the dough until you feel it form a smooth ball.

Place the dough balls in a greased 9x13-pan, 3 rows of 5 rolls each. Cover the pan and let the rolls rise again until doubled, another hour and a half.

When the rolls have almost risen, heat the oven to 350ºF.

Uncover the pan and bake the rolls until they are golden brown, about 25 minutes.

If desired, brush the rolls with melted butter when they are still warm.