This rich, buttery French bread takes about 4 hours (including rise time) but delivers a tender, golden loaf perfect for French toast or sandwiches. Intermediate difficulty — you'll need a stand mixer or strong arms for kneading. The result is bakery-quality brioche with a soft, pillowy crumb.
Take the butter and eggs out of the fridge 30-45 minutes before starting so they come to room temperature. Measure out all your ingredients. Grease a 9x5 inch loaf pan with butter or cooking spray.
In a small bowl, combine the warm milk (should feel like bathwater, around 110°F) with the yeast and 1 teaspoon of the sugar. Stir gently and let sit for 5-10 minutes until it becomes foamy. If it doesn't foam, your yeast is dead — start over with fresh yeast.
In the bowl of your stand mixer fitted with the dough hook, combine the bread flour, remaining sugar, and salt. Add the foamy yeast mixture and 3 of the eggs. Mix on low speed until everything comes together into a shaggy dough, about 2 minutes.
Increase the mixer speed to medium and knead for 8-10 minutes until the dough is smooth, elastic, and pulls away from the sides of the bowl. It should be soft and slightly sticky but shouldn't stick to your hands when touched briefly. If kneading by hand, this will take 15-20 minutes of vigorous kneading.
With the mixer running on medium-low speed, add the room temperature butter one tablespoon at a time, waiting until each piece is fully incorporated before adding the next. This will take about 10 minutes total. The dough will look like it's breaking apart at first — keep going, it will come back together into a smooth, glossy, very soft dough.
Transfer the dough to a large greased bowl, turning it once to coat all sides with oil. Cover tightly with plastic wrap and let rise in a warm, draft-free spot for 1.5 to 2 hours, until doubled in size. It should look puffy and jiggly.
Once doubled, punch down the dough gently to release air. Cover the bowl again and refrigerate for at least 1 hour or up to overnight. Chilling makes the buttery dough much easier to shape. This step is essential — don't skip it.
Remove the cold dough from the fridge. Turn it out onto a lightly floured surface and divide it into 3 equal pieces (use a kitchen scale for precision). Roll each piece into a rope about 10 inches long. Braid the three ropes together, pinching the ends to seal. Tuck the ends under and place the braid seam-side down in your greased loaf pan.
Cover the loaf pan loosely with a clean kitchen towel or plastic wrap. Let the dough rise at room temperature for 1 to 1.5 hours, until it has risen about 1 inch above the rim of the pan and looks puffy. It should spring back slowly when gently pressed.
About 20 minutes before the dough finishes rising, preheat your oven to 375°F (190°C). Position the oven rack in the lower third of the oven for even browning.
In a small bowl, whisk together the remaining egg with 1 tablespoon of water or milk. Gently brush this egg wash all over the top and visible sides of the risen loaf. This will give it a beautiful golden, shiny crust.
Place the loaf pan in the preheated oven and bake for 35-40 minutes. The brioche is done when it's deep golden brown on top and an instant-read thermometer inserted into the center reads 190°F. If the top is browning too quickly after 25 minutes, tent it loosely with aluminum foil.
Remove the pan from the oven and let the brioche cool in the pan for 10 minutes. Then turn it out onto a wire cooling rack and let it cool completely before slicing — at least 30 minutes. Cutting it while hot will make it gummy inside.
Once completely cool, slice with a serrated knife. Store the brioche wrapped in plastic wrap or in an airtight container at room temperature for up to 3 days, or freeze slices for up to 3 months. This bread makes incredible French toast, toast with butter and jam, or gourmet sandwiches.