Step 1- Preheat the oven to 325F, prep a 13 x 9 baking dish by placing aluminum foil inside the dish (this will help once it's all cooked) spray it with cooking spray.
Step 2- Melt the chocolate (carefully, I usually melt it by putting the chocolate bowl in a water bath).
Step 3- Melt the butter and mix with the melted chocolate, then add sugar and mix.
Step 4- Separately, Mix the flour, sugar, and baking powder together.
Step 5 - Add the eggs and vanilla to the chocolate mixture, make sure the egg are completely incorporated, then fold in the dry mix. Add in the chocolate chunks
Step 6- Once everything is mixed, transfer to the baking dish, bake for 30 minutes. Check for doneness you don't want it to be too dry, when you test with a fork or tooth pick a little bit of crumbs should stick to the fork.
Step 7 - Allow to cool for a hour then cut and enjoy!