Combine milk and cream in a medium-sized saucepan over medium-low heat. Stirring occasionally, heat until the mixture reaches a temperature of 170°F and bubbles start to form around the edges.
While the milk mixture is heating, whisk the egg yolks together until smooth in a heatproof bowl. Gradually whisk in the sugar until well incorporated and the mixture is thick and a pale yellow color. Temper the egg yolks by very slowly pouring the hot milk mixture while whisking constantly. Pour this mixture back into the saucepan and heat, stirring frequently, on low heat to a temperature of 185°F. The mixture should be slightly thickened, enough to coat the back of a spoon. It should not come to a boil.
Pour the custard mixture through a fine mesh strainer into a clean bowl in an ice bath to cool the mixture completely, stirring constantly. Cover and refrigerate at least 4 hours or overnight.
Remove the custard from the refrigerator and stir in the vanilla extract and salt. Pour the mixture into an ice cream machine and churn for about 20 minutes (follow your ice cream maker directions).
Once desired consistency, slowly add chopped chocolate to the ice cream maker and churn for 30 seconds longer until mixed through.
Transfer ice cream to airtight container and freeze until solid, about 2 hours.
Use the Best Ingredients - when making ice cream you want to use the best ingredients possible so use free-range eggs and organic milk and cream. Also use high quality products when it comes to added flavorings like vanilla or chocolate. Never use imitation vanilla.
Don't Cut the Fat and Calories - ice cream is not the dessert that you should be cutting the fat. It depends on the high-fat content to create a creamy texture. If you go lower fat, it will cause an icy ice cream. If you're on a diet, just have a smaller scoop!
Add Extract at Right Time - if you add an extract or alcohol while the custard is too hot, you won't get the actual flavor as it will cook out slightly. Just wait until right before you pour the custard into the ice cream maker to add it.
Chill the Custard - you don't necessarily need to chill the custard overnight, but you want to chill until it is as cold as possible.
Use Frozen Bowl - make sure your ice cream bowl has been frozen for at least 24 hours, otherwise you aren't giving the ice cream a great chance of freeze.
Start Ice Cream Motor First - do not pour the custard in the frozen bowl before starting the ice cream maker. It will start freezing upon contact. You want the motor running and slowly pour the custard in.
Don't Overchurn - always error on the side of caution when it comes to churning your ice cream. You do not want it to be hard. Remember it will continue to freeze once you place in the freezer.
Add chocolate at the end – never add your chocolate at the beginning of the process. You want to add it when it looks like there is about a minute left in the churning process.
Keep It Creamy - homemade ice cream can turn hard as we don't add preservatives, however Xanthan gum or a couple tablespoon of vodka will help keep it creamy.