Instructions

1. Whisk 3 cups bread flour, 1/2 cup instant mashed potato flakes, 1/4 cup granulated sugar, 1 tablespoon instant yeast, and 2 teaspoons kosher salt together in a stand mixer.
2. Add 1 cup water and 1 large egg. Mix with the hook attachment on low speed until a soft, smooth dough forms that starts to clear the bottom of the bowl, 5 to 7 minutes. Add 4 tablespoons room temperature unsalted butter and continue to mix on low speed until the butter is fully incorporated, 4 to 5 minutes (the dough will stick to the sides of the bowl).
3. Use a flexible spatula or a plastic bowl scraper to scrape down the sides of the bowl. Cover with a plate or lid. Let the dough rise in a warm place until soft, puffy, and doesn’t spring back when pocked with a finger, 1 to 1 1/2 hours (it does not have to double in bulk).
4. Lightly coat an 8 1/2 x 4 1/2-inch metal loaf pan with cooking spray. (Alternatively, lightly brush with oil or softened butter.) Line the bottom and two long sides of the pan with a sheet of parchment paper that extends over the sides to form a sling.
5. Lightly dust a work surface with bread flour. Turn the dough out onto the floured counter and, using your hands, pat it into a roughly rectangular shape where one side is about 8 1/2-inches long. (The dough may be soft and even slightly tacky but should not be so sticky that it is hard to work with.) Starting at this side, roll the dough up into a log.
6. Place seam-side down in the loaf pan. Cover the pan loosely with lightly oiled plastic wrap. Let rise in a warm place until risen about 1 inch above the top of the pan, 60 to 90 minutes. When the loaf is almost ready, heat the oven to 350°F.
7. Uncover the bread. Bake until the bread is deep golden-brown on top and the center registers at least 200ºF, about 45 minutes.
8. Let the bread cool in the pan for 10 minutes. Flip the bread out onto a wire rack and discard the parchment paper. Let cool completely, about 1 hour.