In a small saucepan over medium-low heat, combine the fresh black raspberries, white sugar, and freshly squeezed lemon juice. Simmer until the sugar is completely dissolved and the berries have softened, stirring occasionally. In a separate small bowl, mix the cornstarch and cold water until smooth, then add this mixture to the berries. Bring it all to a low boil, then reduce the heat and simmer for a few minutes more until thickened. Remove from heat. Blend the berry mixture until completely smooth, using a blender or immersion blender. Next, push the blended mixture through a fine mesh sieve to remove all seeds, discarding the seeds afterwards. Let the strained berry puree cool to room temperature. If preparing ahead of time, refrigerate until needed.

Preheat the oven to 350ºF. In a bowl, thoroughly combine the Nilla wafer crumbs, melted unsalted butter, and ground cinnamon using a fork until the mixture resembles wet sand. Grease a 9x13-inch baking pan and press the crumb mixture evenly into the bottom to form a firm, even crust. Bake in the preheated oven for 8 minutes. Once baked, remove the pan from the oven and set aside. Reduce the oven temperature to 325ºF for the next steps.

In the bowl of a stand mixer fitted with a paddle attachment, beat the softened cream cheese at medium-low speed for about 1 minute to break it up. Add the granulated sugar and beat at medium speed until fully combined, about 1 minute, scraping down the bowl as needed. Next, add the sour cream, pure vanilla extract, grated lemon zest, and fresh lemon juice. Beat again until incorporated, scraping the sides of the bowl occasionally. Finally, add the eggs one at a time and mix until just combined; do not overbeat. The batter should be smooth and creamy.

Pour the prepared cheesecake filling evenly over the baked Nilla wafer crust (from Step 2) in the 9x13-inch pan. Using a spoon, drop dollops of the cooled black raspberry puree (from Step 1) onto the surface of the cheesecake batter. Take a butter knife and gently swirl the puree into the batter to create a marbled effect—don’t over-mix, as you want clear swirls. Bake at 325ºF for 35-40 minutes, or until the edges are set and the center is just barely jiggly. For an extra creamy texture, I like to let the cheesecake bars cool slowly on the counter before refrigerating.

Let the baked cheesecake bars cool to room temperature in the pan, then wrap tightly with plastic wrap. Refrigerate for 6–8 hours, or overnight, to set completely. Once chilled, cut into bars and serve. Store any leftover bars in an airtight container in the refrigerator. I always suggest enjoying these bars well chilled—the flavors really shine through!