Beat the butter and sugar until light and fluffy using a hand mixer or stand mixer for about 2-3 minutes. Add the eggs and lemon juice, mixing until well combined.

In another bowl, combine the flour, baking powder, vanilla sugar, and grated lemon zest.

Add half of the flour mixture to the bowl with the wet ingredients along with the milk. Gently fold the batter with a spatula until thick and smooth. Mix 2 tablespoons of flour with the frozen blueberries in a small bowl*. Add the rest of the flour to the batter.

Spread half of the batter in the bottom of a greased loaf pan.**. Sprinkle the blueberries over this layer. Add another layer of batter and again top with more blueberries. Fold the remaining blueberries into the rest of the batter and spread it in the pan. This way, you avoid the blueberries sinking to the bottom.

Bake the cake at 180 degrees (conventional oven) for 55-60 minutes. The cake is done when a skewer or toothpick inserted into the center comes out clean.

Let the cake cool completely in the pan on a wire rack. Once cooled, remove it from the pan and place it on a wire rack. Let it cool for at least 1 hour.

In a bowl, mix the powdered sugar and lemon juice together. Gradually add milk until you achieve the desired consistency. Pour the glaze over the completely cooled cake and decorate as you please.