Place the chocolate mixture, eggs, sugar and vanilla in a bowl and whisk to combine. Divide the hot cross bun slices between 4 x 1 ½ cup – capacity (375 ml) lightly greased ramekins and pour over the chocolate mixture. Sprinkle with the raw sugar. Place the ramekins in a baking dish and fill with enough boiling water to come half-way up the sides of the ramekins.