Find a heat-resistant dish that fits inside of your stoneware insert. Fit it in and, using a cup or pitcher, pour water around the edges so there is water 1/2 to 3/4 of the way up the sides of the dish. Push it down with your hand if it starts to float up. Take the dish back out. If you have separate dessert ramekins, do the same thing after nestling them all inside.
Whip the 5 egg yolks in a medium-sized bowl and slowly add the cream and baking sugar while mixing. Add the vanilla. Pour mixture into the dish and carefully lower into the stoneware without sloshing water into the dish.