Line the base and grease the sides of a large loaf tin and preheat your oven to 180 degrees (fan forced)
Place the butter, caster sugar and orange rind into your Thermomix bowl and mix for 30 seconds on speed 5 until it's pale and creamy.
Add the eggs 2 seconds on speed 5 to combine.
Add the remainder of your ingredients and mix for 10 seconds on speed 4 or until your mixture is smooth and well combined. Mix for a further 5 - 10 seconds on speed 4 if necessary.
Pour the mixture into your prepared cake tin and place in the oven to bake for 30 - 35 minutes or until the cake is cooked through when tested with a skewer.
Carefully remove the cake from the oven and let it cool in the tin for 10 minutes before transferring to a wire rack to cool completely.
Once cool, prepare the orange icing by sifting 1 ⅓ cups of icing sugar into a bowl and adding 2 tablespoons of orange juice and the grated rind of half an orange. Mix the ingredient together until they are smooth.
Use a spatula or a butter knife to then spread the icing over the cake.