Preheat oven to 350 °F (177 °C). Line two 9x5 loaf pans with parchment paper with enough that they are hanging off both sides for easy bread removal.
In a small bowl, combine all the ingredients for the topping EXCEPT the sparkle sugar. Set the topping mixture aside.
In a large bowl, sift together flour, cocoa, cinnamon, salt, baking powder, and baking soda. Whisk to combine. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, cream together butter and sugar for 2 minutes until light and fluffy. Then add in the eggs, one at a time, incorporating them well after each addition.
In another bowl, whisk together buttermilk, water, and vanilla extract.
Alternating between the dry mixture and the buttermilk mixture, add the contents to the bowl of the stand mixer, mixing at a low speed. Mix until ingredients are well incorporated. You may need to scrape down the sides of your bowl once or twice.
Divide the batter evenly among the two prepare loaf pans. Divide the topping mixture between the two loaves then sprinkle the sparkle sugar on top.
Bake for 45-50 minutes (or longer). Use a toothpick and insert it into the middle of the bread to check for doneness. The toothpick should come out clean when bread is done.
Remove from oven and let cool for 15 minutes before pulling up on the parchment paper to remove the bread from the pan and letting it cool completely on a wire cooling rack. Let cool before slicing.