Perfect Espresso with the Breville Barista Express

0 Power on the Breville Barista Express, secure the portafilter into the group head and let the machine preheat for 10 minutes (ideally).
1 Add 18 grams of coffee beans to the hopper and adjust the internal and external grinders to the appropriate positions (I recommend keeping a small book to remember settings for different beans). For the Lavazza Tierra Organic beans I have my internal grinder set to #1 and the external grinder set to #8 or #9 depending on the bag.
2 Grind the full 18 grams of coffee beans into a dosing cup. Place the portafilter upside down on top of the dosing cup so that it sits flush, then invert both the dosing cup and the portafilter together at the same time so that the ground coffee falls into the portafilter. With the dosing cup still securely fixed to the portafilter, give it a few gentle shakes to aerate and disperse the beans. Then tap the bottom spouts of the portafilter onto the rail of a knock box to help the beans settle.
3 Use a distributor tool to evenly distribute the beans in the portafilter then tamp the beans with a tamper using a light, yet even, pressure.
4 Secure the portafilter into the group head and place a digital scale underneath. Place your cup onto the digital scale and tare the scale. At the same time, press the double-shot button and start a timer. Your goal is to extract 40 grams of espresso in approximately 30 seconds and to produce a rich and thick crema with a full-bodied flavour.
5 If you yield 40 grams of espresso in less than 30 seconds, lower the external grinder by one position for a finer grind. If you yield 40 grams of espresso in more than 30 seconds, raise the external grinder by one position for a coarser grind. Repeat this process, adjusting the external grinder one position at a time, until you yield 40 grams of espresso in around 30 seconds.