Preheat the oven to 190°C.
Peel the beets, then finely grate them - you should get almost two cups.
In a large mixing bowl combine the flour, sugar, cocoa powder, baking powder, baking soda and cinnamon. Add the chocolate pieces, desiccated coconut, then fold in the beetroot.
In another bowl, mix the eggs, milk, vanilla essence, rum and oil.
Combine the two mixtures, then fill the muffin tin and bake for 25 to 30 minutes until the muffins are golden brown.
Transfer them to a wire rack to cool, then scatter some desiccated coconut over them.