01 - In a chilled mixing bowl, whip the heavy cream with powdered sugar and vanilla extract until soft peaks form. Refrigerate until needed.
02 - Scoop 2 portions of pistachio-vanilla ice cream into each of 4 tall glasses.
03 - Slowly pour 200 ml of indigo cream soda over the ice cream in each glass, allowing the soda to foam and bubble.
04 - Spoon or pipe a generous layer of the prepared mousse onto each float, creating a retro milk-bar effect.
05 - Garnish each float with crushed pistachios, edible flowers, or indigo sprinkles as desired. Serve immediately with long spoons and straws.