1. Preheat your oven to 325°F (163°C) and line a 9×13-inch baking pan with parchment paper, leaving some overhang for easy removal.
2. In a medium bowl, combine the graham cracker crumbs, 1/4 cup sugar, and melted butter. Mix until the crumbs are evenly coated.
3. Press the crumb mixture firmly into the bottom of the prepared pan to form an even crust. Bake for 10 minutes, then let it cool slightly.
4. In a large mixing bowl, beat the softened cream cheese until smooth and creamy. Add the sour cream and 1/2 cup sugar, mixing until fully incorporated.
5. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract and optional lemon zest.
6. Pour the cream cheese mixture over the cooled crust, spreading it evenly.
7. Gently scatter the diced strawberries and blueberries over the top, lightly pressing them into the cheesecake mixture.
8. Bake in the preheated oven for 35-40 minutes or until the edges are set and the center is slightly jiggly.
9. Allow the bars to cool to room temperature, then refrigerate for at least 2 hours before slicing and serving.

Remember, it’s okay if the top cracks a little—imperfections are part of the charm. As my kitchen disasters have taught me, sometimes the best flavors come from the unexpected.