Bring 1 cup of the water to a boil. Add ½ cup of the hazelnuts to a small bowl. Pour the boiling water over the hazelnuts and set aside for 30 minutes. After soaking, transfer the nuts along with the water to a blender. Blend until the liquid is smooth. Set aside.
Warm the remaining ½ cup water to between 105°F to 115°F. Add the sugar and the active dry yeast. Stir briefly and then set aside for the yeast to activate. When the yeast is bubbly and risen, after about 5 minutes, proceed with the recipe.
Pulse the remaining ¾ cup of hazelnuts in a food processor until finely ground. Set aside. In the bowl of a stand mixer fitted with a hook attachment, combine the warm hazelnut milk, melted butter, honey, salt, and the yeast mixture. Add the nuts and the flour.
Mix, using the dough hook, until the dough starts to come together. Scrape down the sides occasionally to encourage the dough to come together. If the dough is too sticky and sticks to the side without forming a ball, then add another tablespoon or two of flour.
After 5 minute or so of kneading, take the dough out and lightly knead a couple of times on the counter to bring it together into a smooth ball. Transfer the dough to a greased bowl. Drizzle a little oil on top of the dough and rub it all over. Cover with cling film or a tea towel and then set in a warm place to rise for 1 to 1 ½ hours until double in volume.
After the dough has risen, punch it down to deflate completely. Lightly knead the dough to remove any air bubbles. Divide the dough in half. Shape each half into a long, thin loaf, similar to French bread.
Transfer the loaves to either a French bread pan or a parchment lined baking sheet. Cut 3 or 4 slashes with a sharp knife on top of each loaf. Cover with a tea towel and let rise in a warm place for 30 minutes, until double in volume.
Preheat the oven to 375°F. Make an egg wash by whisking the egg with a teaspoon of water. Brush the egg wash over each loaf. Bake for 20 to 25 minutes until the bread is golden brown and cooked through. The bread should sound hollow when tapped on the bottom.
Let the bread cool briefly before serving. Enjoy!