Truffled Brioche Buns

Bring wine and shallots to a boil in a 12" skillet. Reduce heat to medium-low; simmer until wine evaporates, about 15 minutes. Transfer shallots to a bowl; chill. Meanwhile, heat 1⁄2 cup milk in a small saucepan over medium heat to 115°. Remove from heat; whisk in 1⁄2 cup flour and yeast. Cover with plastic wrap; set aside to let foam.

In bowl of a mixer fitted with a dough hook, add 6 1⁄4 cups flour, sugar, and salt; mix on low speed. Add remaining milk and 3 eggs; mix on low speed. Turn off machine; scrape down sides of bowl with a spatula. With machine on low, add butter, little by little, until smooth. Add yeast mixture; mix until smooth, adding a little flour if necessary, about 8 minutes. Transfer dough to a surface dusted with flour. Knead in shallot mixture and truffles. Transfer dough to a bowl greased with the oil; turn dough to coat. Cover bowl with plastic wrap; let rise at room temperature until dough doubles in size, about 2 hours.

Heat oven to 375°. Line 2 baking sheets with parchment paper; set aside. Punch down dough; transfer to a floured surface. Form dough into 10 balls; divide balls between baking sheets, leaving 3" between each. Loosely cover dough with plastic wrap; let rise for 30 minutes. Brush dough balls with the egg yolk; sprinkle with pepper. Bake, rotating sheets halfway through and moving them from top rack to bottom rack and from front to back, until buns are golden, about 15 minutes. Let cool.