Ratio Cocoa Roasters

Ratio makes all its dark and milk chocolate from scratch. As with wine and coffee, terroir (i.e. the place the beans are grown) and processing make an enormous difference to the final product.

Try the 45 per cent cacao Panama if you're after a safe, nostalgic chocolate. The fruitier Solomon Islands chocolate comes in 58 and 76 per cent varieties, and a citrus-y Peruvian is 70 per cent. If you're feeling adventurous, reach for a 66 per cent bar from Trinidad and Tobago, with notes of rum, raisin and … pepper.

Each bar takes four weeks and eight steps to make. Every part of the process is on show in the long building, where glass screens separate the kitchen from the public seating area. Book a tour if you want to learn more.

Apart from the standard dark and milk chocolates, Ratio also sells varieties with sprinkles of roasted almond; salted caramel; macadamia and lemon myrtle; and apple and cinnamon - all of which are added at the end to prevent nut contamination.

There are more options if you choose to take a seat in attractive blue, grey and white room by St Style. House-made rocky road. Espresso prepared on an under-bench Modbar system. Single-origin hot chocolates with house-made marshmallows. And most interestingly, tea-like hot chocolates made by pouring boiling water over the raw nibs.