Slice the bananas into ½ - ¾ inch pieces and toss them with the honey on a parchment lined baking tray. Bake for 30 minutes, stirring once during baking, until the bananas are browned and cooked through. Scrape the bananas and any syrup into a blender or food processor. Add the coconut milk, lemon juice, pinch of salt and vanilla and puree until smooth.
Chill the mixture in the fridge until cool. Process the mixture in your ice cream maker, scraping down the sides as needed. In the last minutes, pour in the grated chocolate and give it one more churn to incorporate. Transfer it to a container and stir occasionally until frozen. If you like it softer, serve it after only an hour in the freezer, if you want it firmer, let it sit overnight. It will be scoopable after sitting at room temperature for a few minutes.
Garnish the ice cream with some chopped pistachios, toasted coconut or more grate chocolate.