1. Prepare the dough by activating the yeast. Combine warmed milk, a bit of sugar, and yeast in a bowl. Let the mixture rest until foamy, about 5-10 minutes.
2. In a separate bowl, mix bread flour, whole grain flour, salt, ground cinnamon, nutmeg, and cloves.
3. Gradually incorporate the yeast mixture into the dry ingredients. Add brown sugar, melted unsalted butter, and a beaten egg, mixing thoroughly. Knead the dough by hand or using a stand mixer for 8-10 minutes until smooth and elastic.
4. Gently fold semi-sweet chocolate chips into the dough, ensuring even distribution throughout.
5. Allow the dough to rise by placing it in an oiled bowl, covering it with a damp cloth, and leaving it in a warm area for 1-2 hours until it doubles in size. Alternatively, refrigerate overnight for enhanced flavor.
6. Once risen, punch down the dough gently and divide it equally into portions. Shape each portion into a smooth ball.
7. Arrange the dough balls in a greased baking pan, leaving some space for expansion between them. Allow them to rise again for about an hour until doubled in size. Preheat the oven to 350°F (180°C) during this time.
8. Prepare the mixture for the crosses using melted chocolate chips, milk, and flour to create a pipeable paste. Transfer it to a piping bag and pipe crosses over each bun.
9. Bake the buns for 25-30 minutes until golden brown and firm to the touch.
10. Remove the buns from the oven and brush them with a simple syrup glaze made by melting equal parts sugar and water.
11. Allow the buns to cool in the pan, then transfer them to a wire rack. Enjoy freshly baked or toast them slightly before serving for an extra touch of warmth and flavor.