I just want to make a cappuccino which approximates the kind of thing you might get in a high-street coffee shop
Quite tricky to match, because they have very expensive machines. However it’s possible.
1) It needs to be finely ground. Either grind yourself, ask Starbucks to do it when you buy beans, or get the Costa stuff which is occasionally available for paper filter/espresso machine. They sometimes say ‘for all coffee makers’ but this is bollocks. Whilst you won’t die, anything coarse enough to work with cafetiere will be shite in an espresso machine. Grind your own.
2) Run some water through the machine once it’s warmed up, before you make the coffee. Mine says it’s warmed up, but it’s lying. Run at least a cup full of water through first.
This is lovely, for sure, but it’s advanced coffee snobbery. Those two points I made are basics and WILL provide you with drinkable decent lattes and cappucinos, even with supermarket coffee. Also make sure you get the dark/strong roast though – usually labelled ‘5’ for strength. Goes better with the milk, which is why coffee shops usually use a dark roast.
In my experience even the difference between a 20s pour and a 60s pour is subtle, whereas the difference between 5s and 20s is huge. The former being really watery.