1. Begin by turning your oven to the warm setting (or as low as it will go) and move an oven rack to the center position. Whisk 4 cups of flour with the salt and yeast in a mixing bowl.

2. In a microwave-safe container, stir together the mashed potatoes, butter, sugar, and milk. Microwave the mixture until the butter is melted and the mixture reaches 125-130 degrees Fahrenheit on a food thermometer.

3. Pour the heated potato-milk mixture into the bowl of a stand mixer. With the paddle attachment on medium-low speed, add the flour-yeast mixture and the eggs and mix until fully incorporated. Scrape down the paddle and switch it for the dough hook.

4. Slowly add the remaining flour about 1/4 cup at a time while the machine is running on medium-low, stopping to scrape down the dough hook after a couple of minutes. The dough should knead for about seven to nine minutes total. With the machine off and unplugged, gently press your finger into the dough. If it ‘bounces back’ a bit and doesn’t stick to your finger, it’s done. If it sticks to your finger, add another tablespoon or two of flour and knead until the dough pulls away from the bowl. 

5. Remove the mixing bowl from the mixer and pull the dough hook out. Cover the bowl with plastic wrap and leave it for 10 minutes on the counter. This would be a good time to lightly grease/spray your loaf pans. Turn OFF the oven. (You just want residual heat in there for raising the dough.)

6. Dump out the dough onto a clean flourless surface. Knead by hand for a few seconds until it comes together into a nice sort of ‘ball’. With a sharp knife or a bench scraper, divide the dough into three even sections. Cover two pieces with plastic wrap while you roll the third piece of dough into a long rectangle about 1/2 inch thick and 8 inches wide. (It should be about as wide as the loaf pan you plan to bake it in.) Carefully roll the dough from one short end to the other and pinch the seams and ends together. Place the dough, seam side down, in a lightly greased bread pan. Gently press the dough down enough that it touches the sides of the pan. Cover very lightly with plastic wrap. Repeat the process for the other loaf and place pans in the warm oven to rise 35-45 minutes.

7. Gently remove the loaf pans from the oven when they have risen about 1 inch above the rim and place them somewhere draft-free. Heat your oven to 350 degrees Farenheight. Remove the plastic wrap and bake the loaves on the middle rack for about 35 minutes, or until internal temp reaches 190 degrees. Remove loaves and let them cool in the bread pans for about 5 minutes, then gently dump out onto a wire rack (optional: glaze the crust with melted butter). Dump the loaves out onto their sides to cool for approximately 1 hour. Slice and serve, or wrap tightly with plastic wrap and additionally in tin foil to store in the freezer.