A starting recipe for your glass
For a glass of around 300 to 350 millilitres, start with a double espresso, 150 millilitres of cold milk or plant drink and plenty of ice. This starting recipe is intended for home use. Capacity also depends on the glass and ice shape. Add the ingredients one after another and leave room at the top rather than filling the glass to the brim with milk first.
Prepare the espresso using your normal recipe, for example with a drink mass of around 36 grams if that suits the bean and basket. Do not deliberately extend extraction just to get more liquid. If you want less intensity, adjust the milk amount instead. This keeps the coffee base traceable.
The sequence
Fill a clean glass suitable for temperature changes with ice. Add the cold milk and slowly pour in the espresso. A spoon can soften the flow and help create an attractive layered effect. Stir before drinking if you want an even flavour. The layers look good, but they are optional.
Prepare the drink as close to serving as possible. Leaving it standing changes the ratio as the ice melts. Use food-safe ice made from clean water and keep milk chilled. A large warm batch of latte on the kitchen table is not good preparation for later.
Why more ice can make sense
An almost empty glass with two small ice cubes quickly becomes lukewarm. Plenty of cold ice helps cool the mixture rapidly. How much melts depends on factors including starting temperatures, quantity and size. The simple rule of less ice meaning less dilution is therefore unreliable in everyday use.
If the drink tastes too thin, first reduce the milk or choose a smaller glass. You can also experiment with coffee ice cubes, but as they melt they make the drink more coffee-heavy. Label them and handle coffee you have prepared yourself hygienically. The solution need not be any more complicated than a suitable portion size.
Add sweetness thoughtfully
If you would like syrup, start with a small, measured amount and stir it in evenly. Sweetening power varies between syrups. More flavour and more sweetness are not always the same thing, so taste before adding more. A small amount of sugar dissolves more easily in espresso that is still warm.
The espresso should taste decent even without lots of sweetness. Syrup is a flavour choice, not a way to repair heavily burnt or dirty coffee flavours. With plant-based drinks, it is worth checking how much sweetness is already present. The mixture may need no further addition.
Two adjustments that make a difference
For more coffee presence, use less milk next time with the same espresso base. For a milder drink, increase it moderately. If you change the beans instead, keep the quantities the same at first. Note your preferred glass and amounts. Then a chance summer drink becomes a repeatable everyday favourite.