Yes you can! It's a great incubator for making yoghurt.
Please note - A common problem though is that people follow the EasiYo instructions rather than the Mad Millie instructions. EasiYo instructions say to surround it with boiling water, which will kill the culture and it therefore won't work.
You shouldn't surround it with water of 50°C (122°F) or higher. Try surrounding the container with water at around 45°C and you shouldn't have any issues.