Preheat your oven to 350°F (175°C).

In a medium-sized bowl, combine the flour, oats, sugar, and salt. Cut in the cold butter until the mixture resembles coarse crumbs. Press half into the bottom of a greased baking pan.

In a stand mixer, beat the cream cheese with a bit of sugar until smooth. Add egg, vanilla, and spices, then fold in the rhubarb.

Spread the filling evenly over the crust. Sprinkle remaining crust mixture on top.

Bake for approximately 40 minutes until the topping is golden and the filling is set.

Allow bars to cool completely in the pan on a wire rack, then slice into squares.