In a stand mixer, combine the softened unsalted butter and light brown sugar. Beat on medium speed for about 5 minutes until light and fluffy.

Add in two large eggs, vanilla extract, and spiced dark rum to the mixture. Mix on low speed until well incorporated.

Gently fold in the mashed bananas until evenly distributed.

In a separate bowl, whisk together all-purpose flour, baking soda, corn starch, and salt. Gradually incorporate this dry mixture into the banana batter.

Fold the semi-sweet chocolate chips into the dough using a spatula.

Utilizing a large cookie scoop, portion out the cookie dough onto a lined baking sheet, ensuring scoops are about 2 inches apart. Bake in a preheated oven at 350°F for 10-12 minutes or until edges are golden brown.

Allow the cookies to cool on the sheet for a few minutes before transferring them to a wire rack. Whisk together icing ingredients and drizzle over completely cooled cookies.