Preheat the oven to 350°F (175°C) and grease a 9×13-inch baking dish.
In a mixing bowl, cream together the butter and powdered sugar until light and fluffy.
Stir in the lemon zest, cinnamon, nutmeg, ginger, and salt.
Gradually add the flour and mix until a dough forms.
Press the dough into the bottom of the prepared baking dish.
Bake the crust for 15 minutes until set.
In another bowl, beat the cream cheese and granulated sugar until smooth.
Add the egg and vanilla extract, and mix until well combined.
Spread the cream cheese mixture over the baked crust.
Sprinkle the chopped rhubarb over the cream cheese layer.
Bake for an additional 30 minutes or until the filling is set.
Allow the bars to cool completely before cutting into squares.