Preheat oven to 350°. Line an 9x9” pan with foil and spray with cooking spray. Set aside.
Make the cookie layer: mix flour, baking soda, cinnamon, and salt in a medium bowl. Set aside. In the bowl of an electric mixer fitted with the paddle attachment, beat the butter, brown sugar, and ¼ cup granulated sugar until creamy. Add one egg and 1 teaspoon vanilla and beat well. Add the dry ingredients and mix until combined. Stir in the oats and butterscotch chips. Press into the bottom of the prepared pan.
Make the cheesecake layer: Beat the cream cheese with a hand mixer for 1 minute, or until smooth. Add sour cream, remaining 1 egg, remaining ¼ cup sugar, and remaining 1 teaspoon of vanilla and beat until smooth. It's important to start with room temperature ingredients so there will be no lumps. Pour over cookie layer.
Bake for about 35-45 minutes until top of cheesecake looks solid and starts to crack around the edges (mine took about 40 minutes). Cool for an hour and then refrigerate for at least three hours or overnight before cutting into bars.
Optional topping: melt 1/2 cup butterscotch chips with 1 teaspoon vegetable oil on high power in 30 second increments, stirring between each, until melted and smooth. Place melted candy in a sandwich bag and cut off one tip; drizzle over cut bars.