Freeze the cookies before crushing to prevent chocolate from melting and making the crumbs stick together.
Process ice cream, milk, and banana in a blender 15 to 20 seconds or until smooth, stopping to scrape down sides, if needed. Remove and reserve 1 cup crushed cookies. Fold remaining crushed cookies into ice-cream mixture.
Pour ice-cream mixture evenly into 4 serving glasses. Drizzle each with 2 Tbsp. Chocolate-Peanut Butter Sauce. Sprinkle with reserved crushed cookies. Serve immediately.
Note: For testing purposes only, we used Girl Scout Tagalongs cookies.