In the bowl of a stand mixer, add egg yolks and beat on low speed. Slowly add sugar, continue beating until light in color and creamy.
Grate the orange zest into a saucepan containing the half and half. Heat over medium heat until simmering and temper into the egg mixture by adding just a little bit of hot liquid, a few tablespoons at a time, to the mixture with the mixer on low speed. Allow to incorporate before pouring in more.
Once all of the hot half and half has been added to the egg mixture, pour the entire liquid mixture back into the saucepan and heat on medium low heat until the mixture thickens and reaches 175°F - 180°This will take approximately 3 - 4 minutes. The custard should coat the back of a spoon, and not run off when you swipe your finger across the middle.
Pour the hot custard into a fine mesh sieve set over a large bowl containing the room temperature mascarpone. Use a spatula to push the custard through leaving behind the zest and any cooked egg bits.
Stir with a whisk until all the mascarpone dissolves. Add corn syrup, vanilla extract, salt and stir until incorporated. Add orange juice and stir until completely smooth.
Allow custard mixture to cool to room temperature uncovered and refrigerate overnight or until cold enough to use in an ice cream maker (39°F).
Churn in an ice cream maker according to manufacturer’s directions. I churn mine for 20 minutes.
Transfer churned ice cream to an airtight container and freeze for at least 4 hours before serving.