Preheat the oven to 160 C in the air. Lay parchment paper on a sheet metal. Sift the flour and soda into a bowl.

Place half the butter in a non-stick frying pan and melt over medium heat. Allow the butter to brown and smell for an additional 2'-3'. Pour the hot butter into a stainless steel or glass pan. Add the remaining butter and stir to melt well. Add both types of sugar, cocoa, salt and vanilla. Whisk or hand mixer to homogenize the mixture, melt the sugar and cool well. Add the egg and yolk, always beating with a mixer or whisk until the mixture is polished and creamy. Let the mixture rest for 3 - 4 minutes.

We hit it again to fluffy. Using a spatula, add a little flour and stir for 1 minute. Finally add the pieces of chocolate. With a spoon, leave a spoonful of the mixture on parchment paper, leaving 3-4 cm. gap between (spread in baking). Bake for about 15 minutes until the edges are golden brown but the middle remains soft.

After being cooked carefully – they must still be soft – transfer them to a grill to cool and stabilize.