Combine water and milk in a microwave-safe dish and heat in the microwave until you reach a temperature between 105-115F (40-46C). Always stir before checking the temperature!

Pour into a large bowl (or the bowl of a stand mixer) and add yeast and 1 teaspoon of granulated sugar. Stir briefly and allow to sit until yeast is foamy (5-10 minutes). If your yeast does not foam, you will need to start over.

Once yeast is foamy, add remaining 3 Tablepsoons sugar, brown sugar, melted butter, potatoes, egg and egg yolk, salt, and approximately half of the flour. Stir with a wooden spoon (or a dough hook if using a stand mixer) until combined.

Gradually add additional flour as needed until the dough forms a cohesive, somewhat sticky ball that clings together. You may not need all of the flour called for above or you may find that you need more.

Transfer dough to a clean, lightly floured surface and knead until dough is smooth and elastic, about 5-10 minutes. Add additional flour to the dough only as needed as the dough should be slightly sticky for soft, fluffy rolls. (If using a stand mixer, simply use the dough hook and low-speed for this step, it will likely only take about 5 minutes).

Place the dough in a large, lightly oiled bowl and turn so the entire surface of the dough is coated with a thin layer of oil. Cover and let rise in a warm, dry place until doubled in size (about 1-2 hours).

Once dough has rise, gently deflate and transfer to a clean, lightly floured surface.

Divide into ten even-sized pieces and form each into a smooth ball.

Place dough on a baking sheet lined with parchment paper, spacing at least 2-3” (5-8cm) apart (you will likely need two baking sheets).

Cover each sheet with a clean towel and allow to rise in a warm, dry place until increased in size about 50% (about 30 minutes). Meanwhile, preheat your oven to 375F (190C).

Once rolls have risen, remove the towel and lightly brush with egg wash.

Transfer to 375F (190C) preheated oven for about 12 minutes or until baked through and light golden brown (if using two baking sheets, bake one at a time).

Allow rolls to cool on baking sheet and then use a sharp, serrated knife to cut in half. Enjoy!