Slice tin: line a square tin (24cm x 5cm, 9" x 2") with baking/parchment paper, leaving a 1-2cm overhang on all 4 sides (Note 6).
Reserve coconut: set aside 1 tbs of both types of coconut for decorating.
Combine: add milk chocolate, sweetened condensed milk and butter to a large heatproof jug.
Microwave: the ingredients on high for 2 mins. Remove jug, place on heatproof surface and stir. Return jug to microwave and heat on high for a further 1 minute. Remove jug from microwave, place on heatproof surface and stir till consistently combined (Note 7)
Coconut: add desiccated coconut to wet fudge and stir till it is covered by the chocolate. Add shredded coconut to wet fudge and stir till it is also consistently covered by the chocolate.
Fudge into tin: use a large flat spoon to transfer wet coconut fudge to lined tin, spread into all corners and then sprinkle remaining coconut over the top. Pick tin up by the sides and tap gently down onto the bench 2-3 times to ensure there is no bubbles and the fudge is in one flat layer. Place fudge into the fridge to set for a minimum of 1 hour.
Slice: remove fudge from fridge, set on bench for 10 mins, then use a knife to cut into pieces.
Store: in an airtight sealed container, it will last 7 days.