Prepare your pan: Preheat your oven to 350°F. Line a 9x13-inch baking pan with parchment paper, leaving some overhang on the sides for easy removal later.

Make the crust: Mix the flour, softened butter, sugar, and salt in a large bowl until the mixture resembles coarse crumbs. Press this mixture firmly into the bottom of your prepared pan. Bake for 15-18 minutes until lightly golden.

Prepare the rhubarb filling: While the crust bakes, combine the chopped rhubarb, sugar, flour, and cinnamon in a medium bowl. Toss everything together until the rhubarb is evenly coated.

Make the cream cheese mixture: Beat the softened cream cheese and sugar together until smooth and fluffy. Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract and sour cream until completely combined.

Assemble the bars: Once the crust is done, spread the rhubarb mixture evenly over the hot crust. Pour the cream cheese mixture over the rhubarb layer, spreading it gently to cover everything.

Bake to perfection: Return the pan to the oven and bake for 40-45 minutes. The bars are done when the cream cheese layer is set and just slightly jiggly in the center.

Cool completely: Let the bars cool to room temperature in the pan, then refrigerate for at least 2 hours before cutting. This helps them set properly and makes cutting much easier.