Use an electric mixer to cream brown sugar, sugar, & semi cold butter*(you want the butter to be a little cold, I took mine from the frig, microwaved it for 10-14 seconds, cut it into pieces then added it to the bowl).
Add eggs & vanilla, mix.
In a separate bowl mix flour, baking powder, baking soda, & salt together. Add to the creamed butter/sugar. Beat with mixer until everything is mixed in.
Hand stir in both kinds of chocolate chips.
Scoop 2½ tablespoons of cookie dough into a ball (golf ball sized) & drop onto greased cookie sheet. (I used a large cookie scoop/ice cream scoop). Don't touch the dough with your hands or it will warm it up too much. If you want to use your hands then you will need to place the cookie sheet in the frig for 15-20 mins. before baking so the cookies don't go flat.
Bake 10 minutes or until the edges are just starting to brown.
Recipe by THE SEMISWEET SISTERS at https://www.thesemisweetsisters.com/2021/10/25/thick-dark-bittersweet-chocolate-and-semisweet-chocolate-chip-cookies/