In a large saucepan, melt butter over low heat.
Add big marshmallows and stir until completely melted. Remove from heat.
Add Rice Krispies cereal and 2 cups of chopped snickerdoodle cookies. Stir until well coated.
Pour half of the Rice Krispy mixture into a prepared 9x13 pan. With a clean hand press down slightly, you will press down more in the next step.
Add remaining chopped snickerdoodle cookies in an even layer and press into the Rice Krispy mixture. Cover with remaining Rice Krispy mixture and press flat with a clean hand coated in cooking spray or butter.
Evenly pour 2 cups of mini marshmallows over top and gently press into the bars.
Allow bars to cool and serve.