1 ½ cups whole-wheat flour, 1 cup bread flour, 2 ¼ teaspoons instant or rapid-rise yeast, ¾ teaspoon table salt
In the bowl of a stand mixer fitted with the paddle attachment, whisk together the whole wheat flour, bread flour, yeast, and salt. Lock the mixer bowl into place.
1 ½ cups water, 2 tablespoons unsalted butter, cut into 4 pieces, ¼ cup honey
In a 4-cup liquid measuring cup or a medium microwave-safe bowl with a spout, combine the 1 ½ cups water and the butter. Heat in the microwave until the butter is melted and the water is hot, about 2 minutes. Add the honey and whisk until the honey dissolves. Let cool until just warm, 5 to 10 minutes (if you have an instant-read thermometer, you can check the temperature; make sure it’s not more than 130°F, which will be too hot for the yeast).
Start the mixer on low speed. Slowly pour the warm water mixture into the flour mixture in a thin stream and mix until a sticky dough forms, about 1 minute. Increase the speed to medium and mix the dough for 5 minutes. Stop the mixer.
Cooking spray
Spray the inside of an 8 ½-by-4 ½-inch loaf pan and a rubber spatula with cooking spray. Use the greased spatula to scrape down the paddle and the sides of the bowl. Scrape the dough into the greased loaf pan. Use the spatula to push the dough into the corners of the pan and spread it into an even layer. Spray a piece of plastic wrap with cooking spray, then drape it loosely over the loaf pan.
Let the dough rise until it’s level with the edge of the pan, 30 to 45 minutes. Meanwhile, set your oven rack to the middle position and heat the oven to 350 degrees.
Very gently remove the greased plastic wrap from the loaf pan, being careful not to rip the surface of the dough if the plastic wrap has stuck to it. Let it continue to rise until it’s about ½ inch above the top edge of the loaf pan, 10 to 20 minutes. (Keep an eye on it! If the bread dough rises too far above ½ an inch from the edge, it can overproof and collapse in the oven.)
1 large egg, 1 tablespoon water
While the dough rises, crack the egg into a small bowl and add the water. Use a fork to beat the egg and remaining 1 tablespoon water together until well combined.
When the bread dough is ready, use a pastry brush to gently paint the top of the loaf with the beaten egg mixture.
Place the loaf pan in the preheated oven. Bake until the bread is deep golden brown, 45 to 55 minutes.
Use oven mitts to remove the loaf pan from the oven and place it on a cooling rack. Let the bread cool in the pan for 15 minutes.
Use a butter knife to carefully loosen the edges of the bread from the loaf pan (the pan will still be hot). Use oven mitts to carefully turn the pan on its side and tip the bread out onto the cooling rack. Stand the bread back up and let it cool for at least 1 hour.
Transfer the bread to a cutting board and use a bread knife to cut it into slices (make sure an adult helps with this). Serve warm or room temperature.