Preheat the oven to 170°C.

Break the chocolate couverture into small pieces in a bowl, cover it with cling film and transfer it to the microwave for 2 minutes at 600-800 Watts, being careful not to melt it completely.

Put the sugar, eggs and olive oil in a second bowl, and mix them well with a hand whisk.

Add the salt and continue mixing.

Remove the bowl with the chocolate couverture from the microwave and mix it with a silicone spatula.

Transfer the melted chocolate couverture to the bowl with the eggs and mix them with a hand whisk.

Put the flour, cocoa and vanillin in a third bowl, and mix them with a spoon.

Transfer the solid ingredients to the bowl with the wet ingredients and mix them well with the spatula.

Add 80 gr. drops of chocolate couverture and mix them with the spatula.

Line a 25×32 cm rectangular baking dish with parchment paper, smeare with butter and sprinkle with cocoa.

Transfer the mixture to the mold and spread it with the silicone spatula.

Sprinkle with the remaining drops of chocolate couverture, put the mold to the oven and bake it for 25-30 minutes on the top grate.