In the bowl of a stand mixer fitted with the paddle attachment, combine the all-purpose gluten-free flour blend, xanthan gum (if using), tapioca flour, granulated sugar, instant yeast, and fine salt. Stir until combined. Add the mashed potatoes, warm milk, eggs, and oil and mix until a sticky dough forms and all the ingredients are evenly incorporated.
Once the dough starts to come together, switch to the dough hook attachment. Continue to knead the dough on medium-low speed for about 2-3 minutes until it becomes smooth and elastic. The dough will be sticky, but avoid adding extra flour.
Cover the bowl with plastic wrap or a clean kitchen towel and let the dough rise in a warm, draft-free place for about 1-2 hours, or until it doubles in size.
Once the dough has risen, preheat your oven to 375°F. Lightly grease a 9x5-inch loaf pan with cooking spray or oil.
Deflate the risen dough to release any air bubbles. Transfer the dough to the prepared loaf pan and smooth out the top with a wet spatula or your hands.
Cover the loaf pan loosely with plastic wrap or a clean kitchen towel and let the dough rise for an additional 30-45 minutes, or until it reaches the top of the pan.
Once the dough has risen again, remove the plastic wrap or towel and bake the bread in the preheated oven for 40-45 minutes, or until the top is golden brown and the bread sounds hollow when tapped on the bottom.
Remove the bread from the oven and allow it to cool in the pan for 5-10 minutes. Then, carefully transfer the bread to a wire rack to cool completely before slicing.
Notes
Feel free to experiment with different gluten-free flour blends, like rice flour, potato flour, or a combination of gluten-free flour. Just keep in mind different flour blends may produce slightly different textures and flavors. Make sure the flour blend you use is suitable for yeast baking.
I always recommend using the spoon-and-level method to measure gluten-free flour. Spoon the flour into the measuring cup, then level it off with a knife. Don't scoop the flour directly from the bag. Doing this packs the flour, and you'll end up using more than what's needed.
The bread dough has risen enough during the first rise when it's doubled in size (about 1-2 hours). The second rise is complete when the dough rises to the top of the loaf pan. I like to perform the 'finger test' to check if the dough is ready for baking. Gently press your finger into the risen dough; if the indentation remains, it's ready for baking.
Different environments will affect the dough's rising time. If it's a warm and humid day, the dough may rise faster than on a cold and dry day. Use my timings as a guide, and keep an eye on your dough.
Don't use leftover mashed potatoes with any added ingredients, as it'll change the texture and flavor of the bread.
Always deflate the bread dough after the first rise to remove larger air bubbles. This helps create an even crumb in your gf potato bread.
Grease the loaf pan lightly with oil or cooking spray to stop the bread from sticking.
Let your gluten-free bread cool before slicing - bread will collapse if cut while still hot!
To Store: Keep in an airtight container at room temperature for 2-3 days. It'll keep longer in the refrigerator. Slice only when ready to serve rather than pre-slicing the whole loaf.
To Freeze: Let cool and wrap in plastic wrap. Store in a freezer-safe container for 2-3 months. Let it thaw overnight in the refrigerator.