Preheat the oven to 350 degrees
Using a small sauce pan, melt the butter and 5 oz of chocolate chips on medium heat stirring consistently until melted
Set aside to cool slightly
In a large mixing bowl, combine the sugar, eggs and vanilla. Beat on medium speed until combined
Gradually mix in the melted chocolate
Slowly and in the flour
Mix in 1/4 C each of the chocolate chips and semi sweet chocolate chips
Spray your cast iron with pam spray and pour in your brownie mixture
Sprinkle the remaining chocolate chips onto the top of the batter
Place cast iron into the oven for about 25-30 minutes
Once done, Let cool for 5 minutes