Beat the end-of-summer heat with these vanilla bean cream soda floats made with homemade cream soda poured over vanilla ice cream.
In a large saucepan, whisk together the water and sugar. Make a slit to the vanilla bean lengthwise and scrape the seeds into the pan, then add the whole vanilla bean. Bring to a boil over medium heat, whisking often. Boil for another 1–2 minutes or until the sugar has fully dissolved. Remove from the heat and whisk in vanilla extract. Cool to room temperature.
Right before serving, remove the vanilla bean pod from the vanilla syrup, then stir in seltzer and alcohol, if using. Scoop ice cream into serving glasses and pour soda over top. Serve immediately.