1. Preheat the oven to 350°F (175°C). Grease a 1.5 to 2 liter cake pan with butter and dust it with breadcrumbs.

2. In a large mixing bowl, beat the eggs and sugar until light and fluffy.

3. Add the grated lemon peel and juice to the egg mixture, and whisk until fully incorporated.

4. In another bowl, combine the flour, baking powder, and vanilla sugar.

5. Gradually add the dry ingredients to the egg mixture, alternating with the melted butter and milk. Mix until just combined.

6. Pour the batter into the prepared pan and scatter the blueberries evenly on top.

7. Bake in the lower part of the oven for about 45 minutes, or until a toothpick inserted in the center comes out clean.

8. Allow the cake to cool in the pan for 15 minutes, then carefully turn it out onto a wire rack to cool completely.

9. Just before serving, dust the cake with confectioner's sugar and decorate with additional grated lemon peel.