Citrus Twist Bread

Name: Citrus Twist Bread
Ingredients: For the dough:; 1/3 cup warm whole milk (110°F); 2 teaspoons active dry yeast; 1/3 cup granulated sugar, divided; 2 cups all-purpose flour; 1/2 teaspoon kosher salt; 1 large egg, plus 1 large egg yolk; 4 tablespoons (1/2 stick) butter, at room temperature; For the filling and to finish the bread:; 2 tablespoons freshly grated orange zest; 2 tablespoons freshly grated lemon zest; 1 tablespoon freshly grated grapefruit zest; 6 tablespoons granulated sugar; 3 tablespoons unsalted butter, at room temperature; 1 pinch kosher salt; 1 large egg, beaten; Confectioners’ sugar, for dusting (optional)