Melt butter in Thermomix by placing cubes of butter in bowl and melting for 2½ minutes, 70 degrees on speed 2.
Add in flour, coconut, sugar, 2Tbsp cocoa and vanilla and process 20 -30 seconds on speed 3
**Tip out and press into lamington tin. If you're not using a silicone tin then line your tin so you can just lift out the slice
Bake in 180 degrees oven for about 20 minutes. The centre may still appear still soft but the slice will harden up and you don't want to burn your edges.
Grab a small bowl and combine icing ingredients and whisk together well.
Spread over cooled slice, sprinkle with some extra coconut and slice and serve.
I couldn't wait to ice and eat mine so I had warm slice with icing. It was perfect but you'll get a neater slice and presentation if you can leave it. I couldn't.
If you don't have a Thermomix just combine all of the base ingredients, mix well and follow from **.
Recipe by Retro Mummy at https://retromummy.com/2013/02/10/old-school-chocolate-slice/