Chill 2 cans of coconut milk in the refrigerator for at least 6 hours, preferrably overnight.
Open the 2 cans of chilled coconut milk. The cream should have risen to the top. Carefully scoop the cream into a mixing bowl. (Reserve the coconut water that has separated from the cream to use in a smoothie.) With an electric beater or a stand mixer, whip up the coconut cream on high speed for 3-4 minutes until it's light, fluffy and looks just like whipped cream.
Add the condensed coconut milk and whip on high speed for another 2-3 minutes or until thickened. Stir in vanilla extract if desired. Add in the mashed banana and whisk together until the banana is mixed throughout.
Transfer to a lidded container and freeze for 4 hours or overnight. This will last in the freezer 6-8 weeks. As this ice cream does freeze harder than my other just give it a few minutes at room temperature to make it easier to scoop.