1. Slit vanilla bean lengthwise. Scrape seeds into a bowl. Discard pod or make vanilla sugar for later use. Whisk in egg yolks until pale yellow. Set aside.
2. In a medium saucepan over medium-low heat, stir sugar with water until sugar is dissolved. Cook, stirring constantly, until deep amber color.
3. Remove from heat. (Be careful to avert your face and hold the saucepan away from you because cold cream meeting hot caramel means dangerous spatters.) Add cream and milk, stirring until foaming subsides. Return to heat. Cook, stirring constantly, for 5 minutes or until a velvety caramel sauce forms. Gradually whisk into the egg mixture.
4. Transfer entire mixture to a clean saucepan. Cook over low heat, stirring constantly, until the mixtuer is thick enough to coat the back of a wooden spoon. Be careful not to let it boil. Strain into a clean large bowl. Let cool to room temperature. Cover and refrigerate until completely cold or overnight.
5. Stir cream mixture. Transfer to an ice cream maker and freeze according to manufacturer's instructions.