Add the yeast, warm water, melted butter and honey to the bowl of a stand mixer. Stir and let the mixture stand for 5–10 minutes, until the yeast looks creamy and foamy.
1½ teaspoons active dry yeast, 1¼ cups water, 3 tablespoons unsalted butter, 2 tablespoons honey
Add half of the Einkorn flour and all of the salt. Mix on low speed with the paddle attachment until combined.
2 cups einkorn flour, 1½ teaspoons kosher salt
Add the remaining flour and mix on low just until no dry patches remain. The dough will be soft and sticky and will not pull away from the sides of the bowl. Do not add more flour.
2 cups einkorn flour
Use a bench scraper or sturdy spatula to gather the dough into a ball. Transfer it to a buttered bowl, cover and let it rise for about one hour. It should look puffy and increase by roughly 40%, but it should not double.
Thoroughly butter a 9 × 5-inch loaf pan or add a silicone loaf-pan liner.
Turn the dough onto a very lightly floured or lightly buttered work surface. Gently press it into a rectangle about the width of the loaf pan. Roll the dough into a loaf, using the bench scraper to help lift the sticky dough if needed.
Place the loaf seam-side down in the prepared pan. Cover with buttered plastic wrap and let it rise in a warm place for 30–40 minutes. The dough should look noticeably puffy but should not double.
While the dough rises, preheat the oven to 375°F. For a shiny crust, lightly brush the risen dough with the beaten egg white before baking.
1 egg white
Bake for 40–45 minutes, until the crust is golden brown and an instant-read thermometer inserted into the center registers 200°F.
Let the bread cool in the pan for 10 minutes. Remove it from the pan and place it on a wire rack to cool completely before slicing.