In a mixing bowl, combine the crushed vanilla wafers with melted butter until the mixture resembles wet sand, about 2-3 minutes. Press the mixture firmly into the bottom of a lined 12-cup muffin tin.

Using an electric mixer, beat the softened cream cheese in a large bowl until smooth. Gradually add sweetened condensed milk, then mix in mashed banana and vanilla extract. Fold in whipped topping gently.

Place a banana slice on top of each crust, then spoon or pipe the cheesecake filling generously over the banana slices, filling each cup to the top.

Cover the muffin tin with plastic wrap and place it in the refrigerator. Allow cheesecakes to chill for 1-2 hours, or freeze for 30 minutes for firmer texture.

Once set, top each cheesecake with a dollop of extra whipped topping and a mini vanilla wafer. Add banana slices just before serving.