In a large bowl, whisk together sugar and egg yolks until thickened and pale yellow. Set aside.
Add the half and half and cereal to a medium saucepan. Place over medium-low heat and bring to a simmer. Cook at just a simmer for 15 minutes, stirring often. Pour through a fine mesh strainer into a clean bowl.
Slowly whisk the strained hot half and half mixture into the egg mixture. Once completely combined add back to the saucepan and place over low heat. Stir constantly until thickened and the mixture will coat the back of a spoon. Strain mixture again into a clean bowl. Cover with plastic wrap and allow to cool at least 3 hours.
Once cooled, stir in the heavy cream and vanilla extract. Place in refrigerator until completely chilled, preferably overnight. Stir then freeze according to your ice cream machine directions.