Preheat the oven to 170C (350F).
Thoroughly grease the bundt pan or use spray release over the entire interior.
Use an electric hand mixer (or stand mix if you have one) to cream the butter and sugar until it is a fluffy consistency.
In a separate bowl add the gluten free flour, shredded coconut, baking powder, coconut milk powder and tapioca starch and set aside
In another bowl crack the eggs and pour the coconut milk, rum essence and vanilla into the same bowl.
Pour half of the egg/milk mixture into the bowl with the butter/sugar then add half of the flour.
Continue to mix everything together for a minute before finally adding the remaining wet and dry ingredients.
Mix the cake batter for 2 minutes so all the ingredients are fully combined.
Carefully pour the cake batter into the bundt pan and smooth evenly with a spatula (or pallet knife if you have one)
Bake in the oven for 40- 50 minutes (my bundt cake was golden around the 40-45 minute mark).
Insert toothpick or skewer into the cake to determine it's readiness, if it comes out clean, the cake is ready. If not, bake for another 5-10 minutes and test again.
Once baked, remove the cake from the oven and place the cake (still in the pan) on a cooling rack.
Leave the cake to cool down for 10 minutes.
While the cake cools down, get the rum syrup ready by melting the butter on medium heat in a saucepan, pour in the water, sugar and stir until combined.
Bring the mixture to a boil then reduce the heat to medium and continue to stir for 1o minutes.
Remove the saucepan from the stove and stir in the rum essence.
Invert the cake onto a plate or serving platter, if the cake doesn't release from the bundt pan immediately, gently tap the pan a few times until the cake comes out.
Poke a few holes about 1cm apart using a toothpick or skewer at the top of the cake.
Use a pastry brush to evenly glaze the top and sides of the cake. Repeat a few times to apply a thicker coat. Then carefully and very slowly pour the remaining syrup onto the cake.
Store the cake at room temperature for up to 3 days.