1. Bring evaporated milk and sugar to a boil, reduce to simmer, stirring frequently for 25 minutes or until reduced to 12-14 oz. Cool.
2. Preheat oven to 300 degrees. Place pan of water on the bottom rack.
3. Crush cookies in the food processor and press into a buttered 9×13 pan to make a crust.
4. Cream milk mixture, cheese, eggs, and vanilla until smooth.
5. Toss chocolate chips in flour and fold into cheese mixture. Pour over crust.
6. Bake for 1 hour on the middle rack or until set.
7. Chill for at least an hour.
8. Garnish with whipped cream and chocolate shavings (optional).