Melt the butter and chocolate in a steam bath, then add the vanilla essence.
Allow the melted chocolate to reach room temperature.
While the chocolate is cooling, beat the eggs and sugar until they double in volume and turn into a light-colored airy foam (about 7 minutes).
Add the cooled melted chocolate to the foam.
Sift the dry ingredients (flour, salt and the three tablespoons of cocoa), then fold the cream in, mixing carefully to avoid lumps.
Line a baking tray with parchment paper and pour in the mixture, levelling the surface with a wide knife. Sprinkle the raspberries on top, pushing them gently into the mixture until they are three-quarters submerged. The melted chocolate makes this a dense mixture, so the raspberries will sit on top if you don't give them a push.
Place the brownies in a preheated oven at 180°C/356° F for 20-25 minutes. Reduced the baking time a bit if you wanted a more moist consistency, as in the photos.