1/3 cup warm whole milk (100ºF), 2 ¼ teaspoons active dry yeast, 1 large egg, 1 cup unbleached all-purpose flour, 1 cup whole wheat flour
Mix all except one cup of flour until the sponge comes together. Cover the sponge with the remaining flour. Let rest uncovered for 30 to 40 minutes. When the dough has appropriately risen, it will have a “crackled” appearance.
1/3 cup sugar, 1 teaspoon kosher salt, 4 eggs, lightly beaten, 1 ½ cups all-purpose flour, 1 ½ sticks (6 ounces) unsalted butter at room temperature
Mix all ingredients together except for one cup of flour. Mix on low in a mixer with the hook attachment or knead by hand, 15 minutes, scraping the dough down periodically. Slowly add the remaining flour as the dough is mixing. To incorporate the butter, add a little at a time on medium speed. When you have added all the butter, turn the mixer up to medium-high for five to 10 minutes.
When the dough is done mixing, it should be sticky, soft and smooth. Place in a large buttered bowl, and rest covered for two to two-and-a-half hours until nearly doubled in size.
Lift up dough and set aside to de-gas. Rest in the refrigerator for four to six hours, covered tightly with plastic. Preheat the oven to 400°F. Dice 6 ounces of high quality bittersweet chocolate. Divide dough into 1 ¾-ounce pieces. Poke an indentation into each piece of dough, add two tablespoons of chocolate and pull edges of dough around the chocolate. Put the dough edge-side down into a buttered, fluted brioche pan or soufflé dish. Cover lightly and proof for 25 minutes. Brush each brioche with a mixture of egg and a dash of coffee or tea. Bake for four minutes. Lower temperature to 350°F, and bake for eight more minutes. Remove from oven and cool for 10 minutes.