Whip the cream until stiff and chill. Rinse 1 lime hot, grate dry and cut into slices. Squeeze 2 limes. Put ice cubes, lime juice, 1 tablespoon brown sugar, coconut milk, milk and peppermint liqueur in a cocktail shaker. Shake the shaker until the outside of the shaker is fogged up.
Add cream and mix. In 4 bulbous glasses. Roll the lime slices in 2 tablespoons of brown sugar, cut them in and place them on the edges of the glass. Decorate with mint if desired.