Total time includes 12–18 hours hands-off steeping; active time is 10 minutes. Cold brew concentrate keeps 5 to 7 days in a sealed jar in the fridge. Sweet cream keeps about 4 days and needs a good whisk or shake before pouring. Freeze extra concentrate in an ice cube tray so your glass never waters down. Dairy-free: swap coconut cream for the heavy cream and oat milk for the milk — the layer will be a little softer but still sets up beautifully. This recipe is vegetarian and gluten-free.