Butter the soufflé molds with a brush and soft butter vertically (in the direction of the soufflé growth) then make a collar with the soft butter on the edge of the mold. Put sugar in the mold and shake until it covers the whole mold and remove the excess sugar.
Melt the chocolate with the butter in a bain marie or in the microwave.
Mix the sugar with the dry whites.
Whip the egg whites and tighten with the sugar and dry whites mixture. (like a meringue) Be careful to make the bird's bill.
Add the egg yolks to the melted butter chocolate mixture and add a small part of the meringue, quickly relax using a maryse, then gently fold in the rest of the meringue like chocolate mousse.
Place the mix in the bottom of the buttered and sweet soufflé molds. Smooth well with a spatula and with the edge of your finger passed over the edge of the mold to peel off the mix from the mold wall.
Bake at 200 ° C in the floor oven for about 10 to 11 minutes or 180 ° C in a fan oven with reduced ventilation for 7 to 8 minutes.
You can make the mix and mold it in advance, keep it in the refrigerator for 2 days without any problem before cooking.