Melt the butter over a low heat, then chuck in the essence and condensed milk. 

Stir to melt it all together and then add the biscuits, walnuts and cocnut.

Mix thoroughly and then press into a tin lined with greased baking paper. 

Put it in the fridge and make the icing.

Mix the lot together. Add more icing sugar if it's too runny. Slap it on top of the base and put the whole thing back in the fridge till it sets.