Step 1

Heat half-and-half, sugar, light corn syrup, and vanilla. Before we can toss everything into the ice cream machine, we'll need to turn them into a custard. Whisk together all of these ingredients in a medium saucepan. Heat over low heat, constantly whisking to prevent a skin from forming. Bring almost to a simmer, then remove from heat immediately. When it's ready, the mixture should coat the back of a metal spoon. The light corn syrup makes the end result denser and fudgier than a regular ice cream recipe that only uses sugar. You could use honey instead, but use a little less to avoid overpowering the other flavors.

Step 2

Beat the egg yolks. Separate the egg yolks. Beat them in a separate bowl or mixer until slightly thick.The main difference between a custard base and an ice cream base is the number of egg yolks. If you enjoy extremely rich, smooth, eggy custard, you can increase this to six or seven egg yolks.

Step 3

Temper the eggs with the milk mixture. Pour a thin stream of the hot milk mixture into the eggs, whisking constantly. You must pour very slowly and whisk vigorously to avoid cooking the eggs. You can stop once once the eggs are thoroughly combined with about half of the milk mixture.Alternatively, pour a small spoonful of milk into the eggs, whisk while counting to ten, and repeat. This is slower, but less likely to cook the eggs.Keep the bowl stable by placing a rolled-up towel around it. This allows you to whisk with one hand while pouring with the other.If you notice any bits of scrambled egg, strain them out and temper the rest more carefully.

Step 4

Heat to form a custard. Pour the tempered mixture back into the saucepan with the rest of the milk. Heat over medium-low heat, stirring frequently. Remove from heat once the mixture thickens enough to coat the back of the spoon, and leaves a line behind when you run a clean finger through the coating. If you have a cooking thermometer, bring the mixture to 170ºF (75ºC).Again, if you notice any lumps, strain them out before you continue. Remove the vanilla bean pod as well, if using.

Step 5

Stir heavy cream and salt into the custard. Pour the custard into a bowl and stir in the heavy cream until combined. Stir in a little salt as well, less than you would for a regular ice cream base. Frozen custard is warmer than ice cream, which makes salt and sugar seem stronger-tasting.

Step 6

Cover in plastic wrap and chill. Press a sheet of plastic over the custard to prevent a skin from forming. Chill the bowl in a cold refrigerator, and/or in an ice bath as well. For best results, chill for 4–8 hours. You can continue after an hour or two as long as the custard is cold to the touch, but the end result will be chewier.Keep the custard in the coldest part of the fridge. This is usually the back of the lowest shelf, or the back of the top shelf if your fridge has an ice-making component.A wide, shallow bowl will chill more quickly than a deep one.

Step 7

Churn in an ice cream machine. Commercial manufacturers use a special frozen custard machine, but this recipe is intended for a regular, home ice cream machine. Follow your machine's instructions to freeze the custard base, or set it to churn for 20–40 minutes.If your ice cream machine allows you to control the churning speed, reduce it to the minimum setting. (Most do not have this option.)To make a "concrete," finely chop candy or cookies, freeze them, and add them the machine during the last two minutes of churning.

Step 8

Serve. The custard will melt quickly, so it's best eaten right away. If you prefer a harder frozen custard, stick it in the freezer for a couple hours. Unlike ice cream, this will lose its texture rapidly, and is best eaten within a few hours.