Place eggs and sugar into a stand mixer bowl and whip 8-10 min until fluffy and lemon coloured.
Preheat oven to 190° and place a rack in the centre of the oven. Butter the sides and line the base of a 30cm x 20cm cake tin with straight sides and set aside.
Sift flour, baking powder, baking soda and salt into a bowl.
Add half the sifted flour mix to the eggs and fold in gently with a spatula.
Pour in the melted butter then add the second half of the flour. Combine gently folding with a silicone spatula. A slightly lumpy batter is OK.
Spread into prepared tin and bake 20 minutes or until golden and springing back when you touch it.
Remove from oven and cool for 10 minutes on a cake rack in the tin. Tip it out and cool completely before proceeding. (I like to freeze my cakes prior to frosting or in this case dipping them.)
Cut the sponge into 5cm square pieces. Freeze for a few hours.
To make ganache place chocolate and 300ml cream into a microwave safe bowl and melt on a high power setting for about 2 minutes. Stir vigorously until you have a glossy ganache.
Scatter the toasted coconut over a tray. I suggest doing this in smaller batches as the coconut starts to get all chocolatey, which can be a good thing, but it doesn’t look as good.
Using two forks, dip each lamington into the chocolate and shake to remove excess. Roll in the coconut and place on a wire rack that is on top of a tray. Allow chocolate to set before storing in an airtight container in the fridge. (Some people say the pantry, but in our Aussie weather, I think the fridge is best!)
Alternatively, place milled chocolate into a small bowl and use to roll the dipped lamingtons.
To serve, split each lamington in half and dollop the jam and pipe a generous amount of cream on the bottom of each half. Top with the other half and try to wrap your mouth around it politely. Good luck with that.