Preheat oven to 350 degrees Fahrenheit and line a 9"x13" pan with parchment paper so it hangs over the edges.
Make the snickerdoodle dough by creaming together butter, granulated and brown sugar, eggs, and vanilla in the bowl of an electric mixer. In a separate bowl, stir together flour, baking soda, cream of tartar, and salt. Add flour mixture to wet mixture and mix until combined.
Spread/press 2/3 of the dough into the bottom of the pan on the parchment paper. Dough will be sticky but do your best to spread it evenly.
Make the cheesecake layer by creaming together cream cheese, egg, vanilla and sugar in the bowl of an electric mixer. Spread over the snickerdoodle dough. Dot the cream cheese layer with remaining snickerdoodle dough. I like to grab a little dough and press it flat in my hand, then drop it onto the cream cheese layer.
Sprinkle the cinnamon sugar mixture over the top and bake for approximately 27-30 minutes or just until the edges are set and turning golden brown and center is only slightly jiggly. Cool completely before slicing into bars.