In the bowl of a stand mixer or an electric mixer, cream butter, mashed banana, and the sugars, on low speed for 1-2 minutes.

Increase speed to medium to high and continue beating for another 2-3 minutes until the mixture is light and airy, Scrape down the sides of the bowl with a spatula.

Add in the eggs, one at a time, vanilla extract to the creamed mixture, mixing well after each addition.

In a large bowl add the baking soda, cornstarch, salt, cake our and all-purpose our, whisk to combine.

Add the flour mixture to the butter mixture 1 cup at a time. Mix until incorporated.

Split the chocolate chips, banana chips and candied walnuts into two bowls. Add 1 medium bowl of the chocolate chip banana walnut mixture, and mix on low speed until combined or just use a wooden spoon.

Cover the bowl with plastic wrap. Chill in the refrigerator for at least 30 minutes.

Using your large cookie scoop, scoop out large dough portions. Now using your hands shape the chilled dough into large dough balls

Preheat the oven to 400 degrees.

Cover the entire surface of the dough balls with chocolate banana walnut mixture. Make sure all gaps are covered.

Place the dough balls on a baking sheet lined with parchment paper.

Bake the dough balls on the prepared cookie sheets. Sprinkle each dough ball with crystalized sugar.

Bake in the center rack of the oven for 15 minutes.

Remove from the oven and let cool for at least 15 minutes on the baking sheet.

Serve the cookies once cooled, or store them in an airtight container at room temperature to enjoy later.