In a large pot, heat the corn, cobs, milk, cream, and maple syrup to a boil, stirring once or twice.
Remove from heat. Allow to steep while cooling for 1-2 hours. Remove cobs and puree mixture in a blender. Place mixture into a large saucepan.
In a mixing bowl, whisk together egg yolks, sugar, and corn starch. Mixture will be thick, so add one ladleful of corn mixture. Whisk well.
Heat remaining corn mixture to a simmer and slowly add to egg mixture to temper eggs while whisking.
Pour the mixture back into the same saucepan. Heat over medium heat while whisking continuously. When the mixture reaches 180 degrees Fahrenheit or coats the back of a spoon, pour mixture through a sieve into a bowl (pressing on the solids) set over a larger bowl of ice water to stop the cooking process.
Add the vanilla and bourbon and whisk well. Allow to cool in the water bath.
Cover the bowl of custard with plastic wrap and chill overnight to allow flavors to blend.
Process the custard in an ice cream maker. Pack into an airtight plastic container and freeze.