Preheat your oven to 375°F. While it heats, combine the flour, sugar, and salt in a bowl, then cut in the cold butter until the mixture resembles coarse breadcrumbs. Press this mixture firmly into the bottom of a 9-inch springform pan or similar baking dish, creating an even layer. This butter-based crust will provide the perfect foundation for the cheesecake filling.
In a bowl, toss the cut rhubarb with the sugar and flour until evenly coated. Spread this mixture over the prepared crust in an even layer. Bake at 375°F for 15 minutes—this par-baking helps the rhubarb release its juices and begin breaking down, which ensures better flavor integration with the cheesecake filling. Remove from the oven and set aside.
Lower the oven temperature to 350°F. Using an electric mixer or by hand, beat the room-temperature cream cheese with the sugar until smooth and creamy, about 2-3 minutes. Add the eggs one at a time, beating gently between additions—I find mixing on low speed prevents overmixing, which can create a dense or cracked cheesecake. Stir in the lemon juice, which brightens the filling and complements the rhubarb beautifully.
Pour the cream cheese filling from Step 3 over the par-baked rhubarb layer from Step 2, spreading it gently and evenly. Bake at 350°F for 30 minutes—the filling should be set around the edges but still slightly jiggly in the center when gently shaken. This slight jiggle indicates the cheesecake will set properly as it cools.
While the cheesecake bakes, whisk together the sour cream, sugar, and vanilla extract in a small bowl until smooth. When the 30 minutes are up, remove the hot cheesecake from the oven and spread the sour cream mixture evenly over the top. Return to the oven for 5 minutes—just enough time for the topping to set slightly without curdling. This sour cream layer provides a tangy, creamy contrast to the sweet rhubarb.
Remove the cheesecake from the oven and let it cool completely at room temperature for about 1 hour. Then refrigerate for at least 4 hours, or preferably overnight—I like to make this dessert a day ahead so the flavors meld beautifully and the texture becomes perfectly creamy. This resting time also makes slicing much cleaner. Serve chilled, cutting with a sharp knife dipped in warm water between slices for neat portions.