Butter and line a 22cm x 22cm tin, leaving a
small overhang. Put sugar, cream and Baileys
in a large pan and, stirring slowly, bring it to a
simmer. Make sure the sugar is dissolved (it
will stop feeling grainy on the base of the
pan), then turn the heat up to a rolling boil.
Adjust the heat until the mixture bubbles
without getting too near the top of the pan.
Keep bubbling, stirring occasionally, until a
small amount of mixture dropped into a glass
of cold water will form a soft ball that you can
pick up on the end of a teaspoon.
At this stage, the bubbles will have gone
from being large and unruly to smaller and
more even. Stir in the chocolate and pour the
mixture into the tin. Cool and cut.