Preheat your oven to 325°F (160°C). Line a 9×9 inch square baking pan with parchment paper, leaving an overhang on the sides so you can easily lift the bars out later. Lightly grease the parchment with cooking spray.
In a medium bowl, combine the chocolate graham cracker crumbs and the melted butter. Stir until the mixture looks like wet sand. Press the mixture firmly into the bottom of your prepared pan. Bake for 10 minutes, then remove from the oven and let it cool while you prepare the filling.
In a large bowl, beat the softened cream cheese and sugar together until completely smooth and fluffy. Add the eggs one at a time, beating slowly after each addition just until incorporated. Stir in the sour cream, vanilla extract, and flour. Be careful not to overbeat, as this can cause the cheesecake to crack.
Transfer about 1 cup of the white cheesecake batter into a separate small bowl. Stir in the raspberry jam (or puree) and a drop of pink food coloring. Add a tiny bit of red if you want a deeper “fleshy” look. Mix until the color is uniform. Transfer this pink mixture into a piping bag or a zip-top bag with a small hole cut in the corner.
Pour the remaining white cheesecake batter over the cooled chocolate crust and smooth it out with a spatula. Using your piping bag, pipe “squiggles” and “coils” of the pink raspberry batter over the top to resemble the folds of a brain. You can do two halves to make it look like left and right hemispheres.
Bake for 35 to 45 minutes, or until the edges are set but the center still has a slight jiggle. Turn off the oven and crack the door open, letting the cheesecake sit inside for 30 minutes to prevent cracking. Remove from the oven and cool completely on a wire rack. Refrigerate for at least 4 hours, or preferably overnight, before slicing.