In a large bowl, mash 2 medium overly ripe bananas until smooth
Add 2 egg yolks, 2 teaspoons of pure vanilla extract and a cup of softened butter and mix until combined
Mix in a cup of brown sugar and 3/4 cup of granulated sugar until fully combined
Add 2 1/2 cups of all purpose flour, 2 teaspoons of cornstarch, 1 1/2 teaspoons of baking soda, a teaspoon of ground cinnamon and a teaspoon of salt and mix until just combined
Fold in 1 1/2 cups of chopped chocolate or chocolate chips until they are evenly distributed throughout the dough
Chill or freeze the dough until it has firmed up enough to hold a thumb indent and preheat your oven to 350 degrees while the dough is chilling
Once firm, drop heaping tablespoons of dough onto parchment lined baking sheets leaving 2 inches between each portion
Bake for 12-14 minutes or until the edges of the cookies start to brown just a little bit
Transfer the baking sheet onto a cooling rack for 10 minutes and once the cookies have set up enough to move, transfer them directly onto the cooling rack to continue cooling (they will firm up as they cool)
Optionally, top the cookies with additional chocolate or chopped nuts as soon as you pull them out of the oven
Store leftovers in an airtight container at room temperature, in the refrigerator or freezer