Preheat oven to 400 degrees.
In a large bowl cream together butter, brown sugar and granulated sugar for 3 minutes on medium speed.
Add in eggs and vanilla and mix until well blended.
Mix in flour, cornstarch, baking powder, baking soda and salt until almost incorporated.
Add in mini chocolate chips and 1/2 cup chocolate chunks and finish mixing until the flour is just incorporated.
Place 9 free standing baking papers onto a large baking sheet.
Measure out 1/2 cup of dough and place in the baking paper.
Gently press down dough into the bottom of the paper.
Press in a couple of chocolate chunks to top of each dough round
Bake for 10 minutes or until lightly golden brown.
Let them cool for 5 minutes on the baking sheet then transfer to a cooling rack.
Serve them warm.