01 - 
                Preheat oven to 175°C. Ensure the rack is centered.
              
              
              
                02 - 
                In a medium bowl, combine flour, oats, brown sugar, and salt. Blend in softened butter using a pastry blender or fingertips until the mixture forms coarse, pea-sized crumbs.
              
              
              
                03 - 
                Firmly press half of the crumb mixture into the base of an ungreased 23x23 cm baking pan to create an even layer. Reserve remaining mixture for the topping.
              
              
              
                04 - 
                In a separate bowl, beat softened cream cheese, granulated sugar, and egg together until smooth. Add vanilla extract, cinnamon, and nutmeg; mix until fully incorporated. Gently fold in chopped rhubarb.
              
              
              
                05 - 
                Spread cream cheese and rhubarb filling evenly over the prepared crust. Sprinkle reserved crumb mixture evenly over the filling.
              
              
              
                06 - 
                Bake for 40 minutes, or until the topping is golden brown and set.
              
              
              
                07 - 
                Allow bars to cool completely in the pan on a wire rack. Once cooled, cut into squares for serving.