Peel the bananas and slice them into ¼" rounds. Place them on a plate and cover the plate with plastic wrap. Place the bananas in the freezer for 2 hours, or until frozen.

Place the frozen bananas and the vanilla extract in the bowl of a food processor and pulse until the bananas turn into a creamy texture. Stop the food processor intermittently to scrape down the bowl.

Divide the banana mixture by scooping it onto four of the cookies. Top each cookie with the remaining four cookies and immediately transfer the ice cream sandwiches to the freezer. Allow the ice cream sandwiches to freeze for half an hour before serving.