Sift the flour together with the baking powder.

In a large mixing bowl beat with a mixer the eggs, sugar and lemon extract or zest for 4-5 minutes, until the mixture becomes pale and increases its size.

Gradually add the flour mixture, folding it carefully with a rubber spatula.

Add also the oil, mixing gently until absorbed.

Cover the bowl with cling film and refrigerate for at least 20-30 minutes.

Preheat oven to 350º F/ 180º C. Grease very well the cavities of a madeleine pan and sprinkle with flour on top.

Use a piping bag or a teaspoon to fill the madeleine cavities about ¾ full. Insert 1-2 blueberries in each madeleine.

Bake for about 10-12 minutes or until the madeleines are puffy on top and golden at the sides.

Let cool for 5 minutes and then carefully pull them up with a butter knife.

Clean well the pan before greasing it and flouring it again for the rest of the madeleines.

When all the cakes are at room temperature, dip them in chocolate. Let them dry on a sheet of parchment paper.

Melt the white chocolate on a double boiler. Add the butterfly pea powder. Mix for 5-10 minutes with a rubber spatula, until the powder is dissolved completely and the chocolate has cooled.