Craving something tangy and sweet? Try these delightful Lemon Cheesecake Bars with a zesty lemon crumb topping! 

1. Preheat your oven to 325°F (160°C). Line a 9×9-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
2. In a medium bowl, mix together the graham cracker crumbs, sugar, and melted butter for the crust. Press the mixture evenly into the bottom of the prepared pan.
3. In a large bowl, beat the cream cheese and sugar until smooth. Add the eggs, one at a time, mixing well after each addition. Stir in the sour cream, lemon juice, and lemon zest until fully combined.
4. Pour the cheesecake filling over the crust and spread it out evenly.
5. In another bowl, combine the flour, sugar, salt, melted butter, and lemon zest for the crumb topping. Mix until the mixture resembles coarse crumbs.
6. Sprinkle the crumb topping evenly over the cheesecake layer.
7. Bake for 40-45 minutes, or until the edges are set and the center is slightly jiggly.
8. Remove from the oven and let cool completely at room temperature. Then, refrigerate for at least 3 hours, or overnight, until chilled and set.
9. Once chilled, use the parchment paper overhang to lift the cheesecake bars out of the pan. Cut into squares and serve chilled. Enjoy the burst of lemony goodness!