Preheat the oven to 350ºF/180ºC and grease 13x9 inch baking pan
Melt the and butter and chocolate in a large saucepan over low heat, stirring until melted. Remove from heat.
Whisk in the sugar and brown sugar into the pot with the chocolate mixture and mix well until there is no sign of melted butter left. The mixture should be completely combined.
Whisk in the eggs & egg yolks one at a time, then the vanilla & salt. Mix well until completely incorporated.
With a wooden spoon, stir in the sifted flour and cocoa powder just until it is incorporated. It's important not to over mix the batter at this point. Fold in the chocolate chips.
Spread into the pan. place the pan in the oven and set your timer for 25 minutes.
When the timer goes off, open the oven, pull the shelf out and gently shake the pan. If the brownie wobbles in the middle, it’s not quite done so slide it back in and bake for another 5 minutes until the top has a shiny, papery crust and the sides are just beginning to come away from the pan.
Remove from the oven and cool the brownies for at least an hour before removing from the pan and slicing.
If you are outside the US or Canada, Please use the Metric recipe (by clicking the metric button above the ingredients in the recipe). Ingredients like flour and butter are different from country to country. The metric recipe is not a conversion but a recipe that differs according to the ingredients available in your region (when I lived in the UK, I created the metric recipe using European ingredients). Happy Baking! If you live in US or Canada the 'cups recipe' was tested 15 different times using US ingredients until I got it perfect!TIPS:
This recipe makes a big pan of 24 generously sized brownies. To make 12 brownies cut the recipe in half and use an 8-inch square pan.
Take care in measuring. Measure carefully and accurately. It’s key to getting the best results from a recipe.
Use room temperature eggs. Eggs combine easier when mixing at room temperature and mix more evenly into the batter. Your brownies will have a lighter texture and cook more evenly.
To quickly warm your eggs: Just set them in a bowl of warm water for 10 - 15 minutes. This will allow them to warm all the way through.
Follow the instructionson mixing. Under and over-mixing at different stages can cause greasy or cake-like brownies. Follow the instructions and you’ll have perfect brownies every time!
Mix by hand. For fudgy brownies, always mix by hand. You can use a whisk until adding the cocoa powder and flour and then switch to a wooden spoon.
Don’t over mix. When mixing in the flour only mix until combined. A few lumps are fine. Over mixing creates a cake-like brownie.