Add peeled and cubed potato to a small pot with water and set to high. Let boil for at least 10 minutes until potatos are fork tender.
Add sugar and wamred milk to the bowl of a stand mixer and give a quick whisk. Sprinkle yeast on top. Let side for at least 10 minutes until yeast is activated and bubbly.
Drain and mash potatoes with a potato masher or a fork.
Once yeast is activated, add salt, eggs, melted (cooled) butter, mashed potato, and pineapple juice and mix on medium for 1-2 miutes until egg yolks are broken.
Slowly add the flour about 1 cup at a time while dough is mixing on medium-low / medium. Once all of the flour is added, turn up to medium and let mix for about 1-2 minutes until a super sticky dough is formed.
Lightly oil a large bowl and add sticky dough to the bowl. Cover with plastic wrap and let rise for 1-2 hours, until dough has doubled.
Once the dough has doubled, grease a loaf pan. Sprinkle some bread flour around the edges of the risen dough and gently pull it away from the edges of the bowl. In the bowl, form it into a rough rectangle shape, then fold down the top 1/3, fold up the bottom 1/3 and then gather in the ends to make a short, thick log. Add the log, seam side down, to the greased loaf pan.
Cover pan with a linen towel or napkin and let rise another 20-30 minutes, just enough so that the dough has filled out the loaf pan. Pre-heat oven to 325 degrees and move rack to bottom 1/3 of the oven, just one below the middle rack.
Once dough has risen again, use a bread lame or very sharp knife to add three scores to across top of the bread loaf. Keep them at about a 45 degree angle and 1/4 - 1/2 inch deep.
Place loaf pan to the bottom 1/3 rack and bake for 65 minutes.
Remove from oven and gently remove bread from pan and let cool on its side on a cooling rack for at least 1 hr before slicing. Internal temp of dough should be at least 190 degrees and if you tap the bottom of the loaf it should sound hollow. If you slice earlier than 1 hr, you run the risk of creating a gummy center.
Enjoy!