Cream the butter and sugars

• Beat the softened butter with the light brown sugar and granulated sugar until light and fluffy.
• Add the eggs and vanilla and beat until fully combined.

Mix the dry ingredients

• In another bowl, whisk the flour, cornstarch, baking soda, baking powder and salt together.

Make the dough

• Add the dry ingredients to the butter mixture and stir until just combined.
• Fold in the chocolate chips and chopped chocolate.

Chill the dough

• Cover the dough and refrigerate to firm it up.

Shape the cookies

• Preheat the oven to 180 °C.
• Scoop balls of dough onto a lined baking tray, leaving space between them.

Bake

• Bake until the edges are golden and the centers still look slightly soft.

Cool

• Let the cookies rest on the tray for a few minutes, then transfer to a rack to cool.