Preheat oven to 350 degrees F. Prepare Tart Dough: In a small bowl, combine oats, whole wheat flour, and all-purpose flour; set aside. In a large bowl, combine cream cheese and butter; beat with an electric mixer on medium to high speed for 30 seconds. Add brown sugar, the baking soda, cinnamon, and the salt; beat until well mixed. Beat in as much of the oat mixture as you can with the mixer. Using a wooden spoon, stir in any remaining oat mixture.