In a medium bowl, melt unsalted butter in the microwave. Let cool.

Pour low-fat buttermilk into a small saucepan. Heat to approximately 110 degrees F. Pour into a large liquid measuring cup. Stir yeast and 1 tablespoon agave nectar into the buttermilk.

Let the mixture sit until foamy bubbles appear on the surface of the buttermilk, about 10 minutes. Whisk in eggs, the cooled melted butter and remaining 3 tablespoons agave nectar.

The next part can be done with a stand-mixer equipped with a dough hook or by hand. In a large bowl, combine all-purpose flour, whole wheat flour, salt, and cinnamon. Whisk to combine.

Add the buttermilk mixture. Mix with a wooden spoon until the ingredients form into a dough. Turn the dough onto a lightly floured surface. Knead for 8 to 10 minutes, adding flour by 1 tablespoon at a time if dough is sticky, until dough is smooth and elastic.

Punch a whole in the center of the dough, and add chocolate and dried cherries.

Knead the chocolate and dried cherries into the dough until they are evenly dispersed. Place the dough into a bowl coated with cooking spray.

Cover with plastic wrap and place in a warm, draft-free place until the dough doubles in size, 2 to 2½ hours.

Turn the dough onto a lightly floured surface and divide the dough into 12 pieces. With the palm of your hand, roll each ball to form a ball. Coat a 9- by 13-inch baking pan with cooking spray. Place the 12 balls of dough into the pan. Wrap tightly with greased plastic wrap. Let the dough rise in a warm, draft-free place for 1 to 1½ hours, or until the rolls double in size and are pressed against each other.

Preheat the oven to 350 degrees F with the rack in the middle position.

Using a small, sharp knife, cut a ¼-inch deep X through the top of each bun.

In a small bowl, whisk together 1 large egg and 1 tablespoon water. Brush the tops of the buns with the egg mixture.

Bake for 25 to 30 minutes, or until the buns are puffed and golden brown. Sit the pan on a cooling rack and let the buns cool in the pan for 5 minutes.

Whisk together powdered sugar, milk, and vanilla. Using a small spoon, drizzle the glaze over top of the buns in an X, in the grooves on the buns. Serve warm or cool to room temperature.