Step 1

Grease or line a 9-inch x 5-inch loaf pan (or slightly smaller) and set it aside.

Step 2

In the bowl of a stand mixer fitted with the paddle attachment, place the flour, xanthan gum, yeast, cream of tartar and sugar. Whisk together with a separate, handheld whisk. Add the salt, and whisk again to combine.

Step 3

Add the milk, butter, vinegar and egg whites, mixing on low speed after each addition. Scrape down the sides of the mixer bowl as necessary during mixing.

Step 4

Turn the mixer to medium-high speed and mix for about 3 minutes. The dough will be thick, smooth and quite wet.

Step 5

Scrape the dough into the prepared loaf pan. Using a wet spatula, smooth the top.

Step 6

Cover the dough with lightly oiled plastic wrap and allow it to rise in a warm, draft-free place for 30 to 45 minutes or until it’s about 150% of its original size.

Step 7

It should be overflowing the top of the loaf pan by at least 1/2 inch when you retrieve it, but it will not have doubled in volume. It may take longer to rise properly in colder, drier weather and less time in warmer, more humid weather.

Step 8

When the dough has nearly reached the end of its rise, preheat the oven to 375°F.

Step 9

Remove the plastic wrap, and using a sharp knife or lame slash the top of the loaf about 1/4-inch deep. If using the optional seeds, brush the top of the risen bread gently with melted butter, and sprinkle with the seeds.

Step 10

Place the pan in the center of the preheated oven. Bake for 45 minutes to 1 hour, or until the internal temperature of the bread reaches about 195°F on an instant-read thermometer. The outside will form a thick, brown crust.

Step 11

Remove the loaf from the oven, and allow it to cool for about 10 minutes in the pan before transferring to a wire rack to cool completely.

Step 12

To freeze this bread, cool completely and then slice, wrap tightly, and freeze. Defrost as many slices at a time as you need in the toaster.