Preheat the oven to 350°F/180°C and place rack in middle position.
Line two baking pans with parchment paper and set aside.
In a medium size bowl add the flour, baking soda, salt and cocoa powder and mix together.
Melt the chopped semi-sweet chocolate in a small bowl using either a double boiler or microwave.
In a separate bowl, cream together the butter and both sugars until mixture is smooth using a hand mixer or planetary mixer with a paddle attachment.
Add in the vanilla and eggs and continue to mix for about one minutes.
Pour in the melted chocolate and mix until combined.
Put in the flour just until the cookie dough starts to form.
Add in the white chocolate chips and mix for additional 10 seconds.
Scoop the cookie dough using a ice-cream scoop and place onto lined baking pam separating them about 2 inched apart from each other.
Place into preheated oven oven and bake for 10-12 minutes or until the edges are firm.
Remove from oven and cool before serving.
Serve and Enjoy your freshly baked triple chocolate cookies.
Store left over cookies in an airtight container