Rinse out a large saucepan with cold water and leave it wet. (This will stop the milk from scalding)
Pour the milk and buttermilk into the saucepan and heat, stirring occasionally until the temperature reaches 80 – 82°C.
Remove from the heat and scoop off the curds with a slotted spoon or small sieve into a cloth-lined colander.
Cover and refrigerate until cold.
For a soft ricotta remove from the colander as soon as it’s cold, or for a firmer ricotta leave in the colander overnight.