1 Steep the coffee beans in milk, cream, with sugar and salt, then strain: Place the milk, 1 cup of the cream, sugar, salt, and coffee beans in a medium saucepan and heat on medium heat until little bubbles form at the edge of the pan and the milk cream mixture is steamy. Remove from heat, cover, and let sit for 1 hour.
After the beans have steeped in the hot milk cream mixture for an hour, strain the mixture and discard the beans.
2 Chill remaining cream in an ice bath: While the beans are infusing the milk cream mixture, place the remaining 1 cup of cream in a medium metal bowl, set over ice water in a larger bowl. Place a mesh strainer over the the bowl.
3 Temper the eggs with the hot milk cream mixture: Return the milk cream mixture to the saucepan and heat on medium heat until once again steamy. Do not let boil. Whisk the egg yolks in a separate, medium bowl. While whisking the egg yolks, slowly add to the egg yolks some of the hot milk cream mixture. It helps to use a ladle for this. You'll want to add about half of your milk cream mixture. (This step is to temper the eggs to help prevent curdling.) Pour the egg mixture into the saucepan with the rest of the milk cream mixture.
4 Heat the ice cream base until it starts to thicken: Slowly heat the custard base on medium heat, stirring with a wooden spoon, until the mixture thickens and coats the back of the spoon. When you can easily run your finger across the back of the spoon and have the mixture not run, take the saucepan off the heat.
5 Strain mixture into chilled cream: Immediately pour the hot custard mixture through the strainer over the rest of the cream in the ice bath. This will help cool down the mixture quickly. Some curdles may have formed, if so the strainer will catch them.
6 Chill several hours: Cover the bowl with plastic wrap and refrigerate for several hours (preferably overnight) until well chilled.
7 Stir in bourbon and vanilla: When ready to process in your ice cream maker, stir in the bourbon and the vanilla extract. Do not use more than 2 1/2 tablespoons of bourbon or your ice cream will not get firm. (Use no more than 3 Tbsp of bourbon, or the ice cream will have a hard time freezing.)
8 Process in ice cream maker: Process in your ice cream maker according to the manufacturer's instructions.
9 Add chocolate chips: Once processed, stir in the chocolate chips and place in a container into the freezer. Let freeze for several hours (to firm) before serving.