Preheat the oven to 315 degrees F.
For the caramel: Pour the sugar into a medium-size, heavy-bottomed frying pan and place over medium-high heat. Make a dry caramel by letting the sugar cook until evenly dark golden brown, 3 to 5 minutes. Remember, the caramel will continue to cook in the oven, when baking the custard, so do not make it too dark or it will taste bitter. Occasionally stir the sugar with a wooden spoon to remove any lumps. When the caramel has reached the proper color, add water (it may splatter) to keep it from becoming too hard. Mix in the water and remove the caramel from the heat. Carefully pour the hot caramel into the bottom of a 2-quart mold. It may be necessary to tilt the mold from side to side so that the caramel completely covers the bottom.
For the custard: Pour the milk and 1/2 cup of the sugar into a non-reactive 2-quart heavy-bottomed saucepan. While the milk is heating over medium-high heat, use a sharp paring knife to slice the vanilla bean in half lengthwise. Separate the seeds from the outside skin by scraping the bean with the knife. Place the skin and seeds in the heating milk. Scald the milk mixture by heating it until bubbles start to form around the edge of the pan. Remove from heat.
Place the remaining sugar, the whole eggs, and egg yolks in a large mixing bowl and whisk until well incorporated. When you add sugar to eggs (especially to egg yolks), it is important to create an emulsion quickly or else a chemical reaction that produces heat will occur. If you do not whisk immediately, this heat will cook the egg yolks and cause lumps in the custard. Continue to whisk while slowly pouring the hot milk into the egg mixture and whisking until the mixture is smooth and homogenous in color. Try not to create air bubbles on the surface of the custard when you whisk, as these can form a crust on the baked custard. Pour the mixture through a fine-mesh sieve to remove the vanilla bean pieces and any overcooked eggs. Sprinkle the cranberries into the bottom of the mold. Then, pour the milk mixture into the mold and place in a roasting pan in the oven.
Traditionally, custard is baked in a hot water bath to insulate it from the direct heat of the oven and to keep the eggs from cooking too fast, which would cause them to separate. Use hot water from the tap and pour enough water into the roasting pan to reach halfway up the side of the mold. When baked correctly, the custard should tremble slightly when gently shaken. In a conventional oven, this should take about 1 hour. If you detect any liquid under the skin, the custard is underbaked. Put it back in the oven and shake it every 5 minutes until it is ready. If the custard begins to bubble during baking, reduce the oven temperature 25 degrees F (14 degrees C).
Remove the mold from the oven and the water bath and place on a wire rack for 30 minutes. Refrigerate for 2 hours before serving; it will finish setting in the refrigerator. Let the water bath cool before removing it from the oven.
To unmold the creme caramel: Carefully run a sharp paring knife around the inside of the mold to loosen the custard. Invert a flat plate over the creme caramel. Place 1 hand on either side, grasping both plate and mold, and flip them both so that the mold is on top. Gently lift off the mold. You may need to tap the bottom of the mold to release the custard. Sometimes I like to serve this dessert with whipped cream. Creme caramel will keep in the refrigerator, well wrapped in plastic wrap, for a couple of days.
This recipe gives a soft and delicate creme caramel but it can be difficult to bake. If you use 5 large egg yolks and 8 large whole eggs, you will have something less delicate but easier to bake because the egg whites are what hold everything together.