Line a large loaf tin with baking paper and preheat your oven to 160 degrees celsius.
Place the softened butter into your Thermomix bowl and mix 30 seconds on speed 3 until it is pale and creamy.
Add the eggs and vanilla extract and and mix for 30 seconds on speed 5
Add the remainder of your ingredients (except the blueberries) 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.
Place the blueberries into a small bowl and sprinkle the extra flour over the top of them. Lightly toss until they are coated in the flour.
Add the blueberries and use your spatula to gently fold them through the mixture.
Pour the mixture into your prepared cake tin and place into the oven to bake for 50 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 carefully transferring to a wire rack to cool completely.
Once cool, prepare the lemon icing by sifting the icing sugar into a bowl and adding the lemon juice. Mix until it reaches a smooth and soft consistency. If your icing is a little too ‘thick’ add ½ tsp of hot water until it’s the right consistency to spread over your loaf.
Use a spatula or a butter knife to then spread the icing over the cake and set aside for 10 minutes to allow the icing to set.