Preheat your oven to 350°F and lightly grease a jelly roll pan (10.5 x 15.5-inch).

In a large bowl, mix together the vegetable oil, granulated sugar, light brown sugar, eggs, and vanilla extract.

In another bowl, combine the flour, oats, baking powder, salt, and cinnamon. Gradually add this mixture to the wet ingredients, stirring until just incorporated.

Fold in the grated zucchini until evenly distributed.

Pour the batter into the greased jelly roll pan, spreading it out evenly.

Bake for 18-22 minutes, or until a toothpick inserted into the center comes out clean, with a few moist crumbs attached. Avoid overbaking. Allow the bars to cool completely.

For the frosting, beat the cream cheese and unsalted butter together until light and fluffy. Add in the powdered sugar and vanilla extract, beating until smooth and creamy.

Once the bars are completely cooled, spread the frosting evenly over the top. Cut into squares and serve.