Active Time 1 hour
Total Time 18 hours
Makes 24 servings
¾ cup whole milk
¾ cup bread flour
¾ tsp active dried yeast
Canola oil, for pans and rising
4 eggs, plus 1 for brushing dough
2¼ cups bread flour, plus more for forming dough
1½ tsp active dried yeast
1½ tsp kosher salt
¼ cup granulated sugar
10 tbsp unsalted butter, at room temperature, cut into small pieces
Prepare the sponge. Warm milk in a saucepan to 75º F (use a cooking thermometer). Combine milk, flour, and yeast in a medium bowl and whisk until all lumps are dissolved. Cover loosely with plastic wrap or foil and let stand at room temperature, 65º to 70º, for two hours.
To make the dough, brush the inside of a medium bowl with canola oil. Set aside. Scrape the sponge into the bowl of your stand mixer. Add 4 eggs, flour, yeast, and salt. Using the paddle attachment, mix on low speed until thoroughly combined, about 2 minutes. Switch to medium-high speed and mix for 6 to 10 minutes, or until dough begins to pull clean from the sides of the bowl. There will likely be a ring of dough sticking to the top of the bowl; scrape it down with a rubber spatula. Pulse the dough a few times, scraping between pulses, until all of the dough is well mixed and sitting in the bottom of your bowl.
Turn the mixer on low and slowly pour in sugar. Increase speed to medium and mix until sugar is incorporated, about 1 minute. With the mixer running, drop butter into the dough one piece at a time until incorporated, 1 to 2 minutes. You may need to scrape down the bowl during this process.
Scrape dough into the prepared bowl and cover with plastic wrap. Let sit at room temperature for 30 to 45 minutes, until it is soft and pillowy and has almost doubled in size. Remove cover and, using your fist, push down the center of the dough. (It will be sticky.) Pull outer edges of the dough up and into the center, and then turn entire ball of dough over in the bowl. There should now be a smooth surface facing up. Cover and let sit for 30 minutes. Transfer covered bowl to the refrigerator for 12 to 18 hours.
Brush muffin tins with butter or canola oil. Remove bowl from refrigerator and place dough onto a lightly floured surface. Divide dough into 24 equal pieces and place each piece onto the floured surface. Pick up one piece of dough, placing the flour-coated side into the palm of your hand. Use a finger to make a slight depression in the center, and then pull the outer edges up and into the depression. Place ball of dough into muffin tin—the side that touched your palm should face up. Repeat with remaining pieces. Cover muffin tins with plastic wrap or a large plastic bag to prevent a skin from forming and let sit in a warm kitchen, about 70º, until dough doubles in size, 30 to 45 minutes. In a small bowl, whisk remaining egg until blended. Remove cover and brush each brioche evenly with egg wash. Cover again and let sit for 30 to 45 minutes.
While brioches are rising, preheat oven to 325º.
Remove cover and place tins on center rack of oven. Immediately reduce heat to 300º and bake for 6 minutes. Rotate tins and bake for another 5 to 10 minutes, or until golden. Allow to cool briefly before removing from pans.