Mix the flour, xanthan gum if using, baking powder and bicarb together

Cream together the sugar and margarine

Put the pineapple chunks, juice, coconut milk, lemon juice and rum essence in a blender and puree

Add it to the creamed margarine & sugar. The mixture will look curdled. Don't worry!

Add into the flour mixture gradually as to avoid the batter clumping

Once it's all mixed in, divide equally between the paper cases

Bake for 25 - 30 minutes or until firm and risen. FYI if you use a muffin tin rather than a cupcake tray they will appear taller and not as spread out

Add the coconut milk and vanilla extract to loosen to a piping consistency and ice the cakes

Sprinkle the desiccated coconut over the buttercream

Add a cherry and a pineapple chunk on top with a trimmed cocktail umbrella for garnish