I understand, but ATK showed that you can do it without a ice cream machine
I just wanted to know how different would it have been if I had used a machine?
"Creating vanilla frozen custard without an ice cream maker requires a few tricks to churn out a smooth, rich, and creamy dessert. First, we heated a mixture of heavy cream, whole milk, corn syrup (to help prevent crystallization), and vanilla. Then, we slowly poured it over a rich mixture of egg yolks, sugar, and dry milk powder–a process called tempering. This helped guard against any clumping of egg in the final custard. Straining the mixture removed any solid bits of egg. To achieve the smoothest possible frozen custard, we cooled the mixture down and then whipped it in a stand mixer to add air, which prevents crystallization and makes the final product especially creamy."