Pre-heatoven 350F (1800 C) with rack in the middle. Line a cookie tray withbaking paper.
Whisk eggs, sugar and vanilla in a bowl . Melt half the chocolate chips and butter in a bowl using bain marie water method till both are melted. You can either melt chocolate and butter in the microwave, until the chocolate is melted.
In a small bowl whisk flour and baking powder together. Whisk the egg mix. Stir in dry ingredients, nuts and remaining chocolate.
Scoop rounded tablespoons of batter 1 inch apart on baking sheet. Bake until the surface of the cookie looks dry and faintly cracked, and the centres are still gooey, 10-12 minutes.
