- Warm 1/3 cup milk and 1 tablespoon brown sugar in a microwave-safe bowl until it reaches 110°F. Stir in the yeast and let it sit until foamy, about 5 to 10 minutes.
- Whisk 1/4 cup flour and remaining 1/2 cup milk until smooth in another bowl. Microwave until smooth, stirring between each interval, for about 1 minute.
- In a stand mixer bowl, combine the yeast mixture, flour mixture, eggs, melted butter, orange zest, salt, vanilla, remaining brown sugar, and 3 cups flour. Beat until the dough starts to pull away from the sides and is slightly sticky, about 10 to 12 minutes.
- Place the dough in a greased bowl, cover with plastic wrap, and let it rise until doubled in size, about 1 hour.