Preheat oven to 350 degrees F. Lightly grease a 13x9x2" pan.
In a large bowl, combine the flour, oats, 3/4 cup brown sugar and butter. Mix until crumbly. Reserve 1 1/2 cups crumb mixture for topping. Press remaining mixture into bottom of greased pan. Bake for 15 minutes or until lightly browned.
In a large bowl, beat cream cheese until fluffy. Gradually mix in condensed milk, lemon juice and vanilla until smooth. Pour evenly over the cooled crust.
In a small bowl, combine remaining 1 Tbsp brown sugar, cornstarch and cranberry sauce. Spoon over cream cheese mixture. Sprinkle with the reserved crumb topping and lemon zest. Bake for 40 minutes and cool at room temp- refrigerate before cutting into bars. Store in refrigerator.