Preheat oven to 350°F (175°C) and line two baking sheets with parchment paper or grease lightly.
In a large bowl, beat softened butter with the brown and granulated sugars until creamy and fluffy, about 2-3 minutes.
Add the egg, extra egg yolk, and vanilla extract; mix until smooth and glossy.
Stir in the mashed banana until combined, ignoring if the mixture looks slightly split.
In a separate bowl, whisk together flour, instant pudding mix, baking soda, baking powder, salt, and cinnamon if using.
Gently fold the dry ingredients into the wet ingredients until no dry streaks remain; avoid overmixing to prevent cakey cookies.
Fold in crushed vanilla wafers and white chocolate chips, reserving a small handful for topping.
Chill the dough for 20-30 minutes to thicken, or bake immediately if short on time.
Scoop dough into 2-tablespoon portions, spacing cookies about 2 inches apart on prepared baking sheets.
Bake for 9-11 minutes until edges are set and lightly golden; centers should appear slightly underdone.
Remove from oven, gently press reserved vanilla wafer crumbs and chocolate chips on top, and cool 5 minutes on the sheet.
Transfer cookies to a wire rack to cool completely or enjoy warm as preferred.