You will need a melon baller and/or disposable gloves.
Break the chocolate in small pieces and place in a large bowl.
Warm the cream in a saucepan until hot but not boiling. Add the butter to the cream. Pour over the chocolate and stir until melted.
Place the mixture in a large rectangular container, cover and refrigerate overnight.
Pour sprinkles (or chopped nuts if using) into different bowls.
Using a melon baller scoop round balls of about 2cm diameter. If you do not have a melon baller, use a regular teaspoon and roll them with your hands. You will need disposable gloves as they can get messy.
Roll each truffle in sprinkles or nuts and set aside.
They look great packaged in glass jars or cellophane bags tied with ribbons.