I started wondering one day what would go together with cinnamon and chocolate in an ice cream. The combination with oatmeal cookies just seemed to be a perfect match, so I tried it. It’s become the most-often requested ice cream I’ve made, and one of the easiest to make. —Ice Cream Geek
Coarsely chop the cookies and chocolate, and place them in the refrigerator to chill. Also pre-chill a bowl large enough to hold all the ice cream after it's been churned.
Mix the cream, milk, and cinnamon together and heat over medium-low heat.
While that’s heating, beat the eggs in a separate bowl until they turn lighter in color. Then very slowly, add the sugar while beating the eggs. When it’s all in there, mix it a minute or so more.
When the cream/milk mix reaches about 140 degrees F (60 C), remove it from the heat. Gradually stir small amounts of the cream/milk mix into the egg/sugar mix until about a third of the cream and milk have been added. Then pour in the rest of the cream and milk and mix it all together.
Heat the mix over medium-low heat, stirring frequently, until it reaches 175 degrees F (79 C) for at least 25 seconds. (That's the FDA's requirement for a pasteurized ice cream mix.)
When the ice cream is finished churning, transfer it from the machine to the chilled bowl and then fold in the cookies and chocolate. Then transfer the ice cream to containers and freeze for several hours before serving.
Notes: I used 8 "Mother's" brand crispy oatmeal cookies, unfrosted and without raisins, and I cut each one like a tic-tac-toe board. I also used 65 grams (2.3 oz) of Hershey's milk chocolate, chopped into small chunks. Other brands should work fine also though.