Bring cream and butter to a boil in a small heavy saucepan and once boiling add the tea leaves and set aside for 10 minutes to infuse.
Place the chopped chocolate in a bowl and return the cream to the heat and bring to a simmer before removing from the heat and pouring through a fine mesh seive over the top of the chocolate. Press the tea leaves to extract all the cream. Stir with a spoon until smooth and then cover with cling film and refrigerate for 3 hours or until firm.
Place the cocoa powder in a bowl and use a melon baller to scoop out the truffles from the ganache and roll in your hands to form a ball before lightly dusting with cocoa powder.
Store the dusted truffles in an airtight container in the refrigerator for 1 week.
Dust your hands with the cocoa powder to help prevent your hands from becoming a sticky mess. If you would like to use a black Earl Grey tea reduce the tea leaves to 2 tsp as black Earl Grey is stronger in flavour. Also if using Milk Chocolate in place of Dark Chocolate reduce the green Earl Grey to 2 tsp as the milk chocolate is not as strong in flavour.