Preheat your oven to 180 degrees Celsius and line a 9" baking tin with parchment. Reserve 1tbsp of the flour for later, then in a large bowl, add the rest of the flour, baking powder, and the salt and mix it all together
To another bowl, add the sugar, melt your butter and add this to your sugar, 2tbsp of the lemon juice, the lemon zest and your eggs. Beat well until combined
Add the tbsp of flour reserved earlier into your blueberries and make sure they are all coated. This stops them from clumping together or sinking to the bottom of your cake.
Add your dry ingredients into your wet and mix well to combine, then add in the blueberries and mix those through. Pour your mix into your prepared tin, then place it into the oven for 1 hour
When ready, remove your cake from the oven. While it cools, prepare a glaze using the icing sugar and remaining lemon juice. Drizzle your glaze on top once the cake has cooled