Place roasting pan 3/4 full of hot water in a 300 degree oven
coat four custard cups with butter and set aside
combine cream, milk and espresso in a small saucepan and scald
whisk together the egg yolks,egg, sugar, vanilla and a pinch of salt in a medium bowl.
while whisking add a little of the hot mixture to the egg mixture , once combined well slowly add the hot mixture to the egg mix while whisking.
Pour into the cups and place in the water bath in the oven. Make sure the water comes up to 3/4 of the outside of the cup.
bake until set, about 35 minutes (knife will come out clean)
once done remove from the water bath and cool.