In a bowl whisk together your egg yolks and sugar until it's a pale yellow. You want it to become thick enough to make a pale yellow "ribbon" if you drizzle it off the whisk (see picture). Set aside.
In a large pot like a dutch oven, over medium heat, warm up the cream and milk until it is hot all the way through but do not boil. Boiling can cause the dairy to separate.
Once the cream and milk are hot, take it off the heat. You will want to temper this into the yolk and sugar mixture. Tempering is a way to add the hot cream into the yolk mixture without scrambling the eggs so that you slowly warm it up before adding it into the hot pot of cream. You will want to take small amount of the hot cream and slowly add it to the yolk and sugar mixture, stirring until it's evenly distributed. You will want to temper 2-3 ladles (or big spoonfuls) worth of hot cream.
After the eggs and sugar are warmed up from the tempering, add it all back into the pot with the remainder of the hot cream and stir to combine.
Heat the mixture over medium heat, stirring on and off. You don't want it to boil or burn. You want it to become thick until it can coat a wooden spoon and you can run your finger through the mixture and it doesn't immediately run back together (see picture).
Remove from heat. Cut your vanilla bean down the middle lengthwise (hot dog). Scrape down the sides of your vanilla bean and add in the vanilla specks. Add in your coffee beans. Let this steep for at least 1 hour. If you want a stronger coffee flavor, steep it longer.
After steeping, strain your coffee beans out and pour the mixture into a bowl. Put the bowl over an ice bath, and stir to help cool it down.Once the mixture is cool, place plastic wrap over the bowl, press the plastic wrap down onto the top of the mixture to help prevent a crust from forming. Cool in the refrigerator until it's cold. I usually wait 12 hours.
Pour your mixture into your ice cream maker and make accordingly to appliance instructions.
I recommend placing it in your freezer for at least an hour to let it set up.