Heat the milk and cream. Heat the milk, cream, 1/2 cup of sugar, and vanilla bean in a saucepan over medium heat, until warm and steaming, or about 170 degrees.
Beat the eggs and remaining sugar. Meanwhile, beat the egg yolks and remaining 1/4 cup of sugar until light yellow in color and well combined. They will noticeably change color when mixed enough. (A hand mixer on low will work well.)
Temper the eggs by adding half of the warm milk mixture, a half cup at a time. Then add the egg mixture back into the saucepan with the rest of the milk and cream.
Heat the custard. Heat the saucepan, which now contains all of the milk, cream, sugar, and eggs, over medium heat, stirring constantly, until it reaches 185 degrees. The custard is ready when it has thickened enough to coat the back of a spoon. Do not boil. Once off the heat, add a pinch of salt, and the vanilla extract, if using.
Strain the custard and add the vanilla and salt. Hold cheesecloth or a strainer over a bowl to strain the custard. Scrape the vanilla beans and add the vanilla bean and vanilla extract along with the salt and stir to combine. Immediately place the custard into in the refrigerator to chill. Chill for 4-24 hours, until very cold.
Freeze ice cream according to manufacturer's instructions. When it has reached the consistency of soft serve ice cream, place into loaf pan, cover with plastic wrap, and freeze until firm. Will keep well, covered in the freezer for a week.