Step 1

Make the coffee. In a large pitcher, combine the coffee and 4 cups water. Stir and refrigerate for at least 8 hours. Line a fine-mesh sieve with a coffee filter or wet paper towel and set over a large bowl. Pour the coffee mixture into the filter and allow to drain. Discard the coffee grounds.

Step 2

Make the syrup. Meanwhile, combine the brown sugar and 1/2 cup water in a small saucepan and bring to a simmer over medium-high heat, stirring until the sugar dissolves and the liquid thickens slightly. Transfer to a container and allow to cool to room temperature.

Step 3

Make the foam. Put the milk and brown sugar in a large bowl. Using a hand mixer or your go-go gadget arm with a whisk, vigorously whisk the mixture until you see it foaming on top.

Step 4

Assemble the coffee. Fill a glass with ice and a tablespoon or so of the syrup, then pour in the chilled coffee. Using a spoon, carefully spoon the foamy top layer of the milk on top of the coffee. You may need to whisk more to get more foam. Finish with a dusting of cinnamon sugar. Serve cold.