Brew 2 cups of strong coffee using your preferred method (brew about 25–50% stronger than usual). Let the coffee cool to room temperature, or chill in the refrigerator for 20–30 minutes. If using espresso powder, dissolve 1/2 tsp into 1 cup cold water to make a concentrated boost and set aside.

Combine cooled brewed coffee and the cold water (and the dissolved espresso concentrate if using) in a pitcher. Stir to combine.

Sweetener & flavor (customize)

Add 2 tablespoons simple syrup (or liquid sweetener) to the coffee mixture and stir until fully incorporated. Taste and adjust sweetness: add up to 1–2 additional tablespoons if desired.

If using vanilla extract or chocolate syrup, add 1/4 tsp vanilla or 1 tbsp chocolate syrup now and stir to combine. These are optional; adjust to preference.

Milk & finish

Fill a tall glass with 1 cup ice cubes (or use 1/2 cup coffee ice cubes to avoid dilution).

Pour 3/4 to 1 cup of the sweetened coffee mixture over the ice, leaving room for milk. Top with 1 cup milk or dairy alternative (adjust amount to taste). Stir gently to combine. For a layered look, pour milk slowly over the back of a spoon.

If desired, top with 2 tablespoons whipped cream and a drizzle of chocolate syrup or a light dusting of cocoa or cinnamon.

Serve immediately with a straw. Stir again before drinking if separation occurs.