1) Preheat oven at 350F (180C). Place parchemin paper on a cookie plate
2) Mix in a bowl the flour, the baking powder and the zest
3) In a small bowl, mix one egg with 1 tb of water. Reserve
4) In a big bowl, whip butter and sugar for 3 minutes at maximum speed. Add remaining 3 eggs, one at a time.Reduce speed and incorporate the flour mix. Add chocolate and nuts and mix delicately with a fork.
5) Split the dough in two parts, form 2 logs of about 10 inches long. Sprinkle some flour on it and put them on the cookie plate. Flatten them till they get to 4 X 11 X 3/4 inches. Paint with the egg mix.
6) Bake in mid-oven for 20 min, till the top is firm. Cool down for 15min.
7) Reduce oven temperature to 300F (150C).
8) Cut the 2 logs diagonally in 1/2 inch slices. Cook in the oven 15min on both sides. Cool down completely.
Go to full version of