In a pot, heat the heavy cream, milk and one tablespoon sugar into warm stage.

In a bowl, beat egg yolks, sugar and corn starch.

Pour half of warm milk into egg mixture. Whisk it well until sugar dissolved.

Pour back the egg mixture into the rest of milk in the pot.

Switch on the heat, add the vanilla bean/vanilla extract.

Keep whisking it until the custard thickens. Test it with the back of wooden spoon.

Cool it down for 2 hours in the fridge. Take it out from fridge, whisk it.

Cool it in the freezer for 3 hours. Take it out from fridge, the middle part of the creams is still soft, whisk it again. This step could be done twice to break a little bit of the crystal ice.

The next day, the custard ice cream is ready to serve. It will not be as creamy as the one making with ice cream machine because by using ice cream machine, it breaks the crystal ice.

Notes. if you do have blender at home, after the custard cream is half freezed, you may blend it in the blender to break the crystal ice. Place it back to freezer and freeze it overnight.