Step 1: In a bowl, mingle the flour, the baking powder, the baking soda and the salt and leave it aside.
Step 2: In another bowl mingle the espresso coffee, the liquid vanilla and the yoghurt.
Step 3: Put in the mixer the butter and the sugar in medium speed until it gets fluffy.
Step 4: Add the eggs stirring them well and add the melted chocolate.
Step 5: Add the flour mixture and the yoghurt mixture and stir well until you get a homogenized mixture.
Step 6: Add the orange zest and stir until you have a soft cream.
Step 7: Preheat the oven in 170 degrees
Step 8: butter and cover with an oil paper a rectangular forma 30 x 15 cm
Step 9: Spread evenly the mixture and bake for 25-30 minutes.