Preheat the oven to 350 degrees. Spray a 9-inch square baking pan with cooking spray and set aside.

Whisk together the flour, cinnamon, baking soda, baking powder, and salt in a medium bowl and set aside.

Combine the sugar, eggs, oil, and vanilla in a large bowl. Beat with an electric mixer until smooth.

With mixer on low, gradually mix in the dry ingredients until just combined. Use a rubber spatula to fold in the carrots and raisins or nuts (if using).

Scrape into the prepared pan and smooth the top. Set aside while you make the topping.

Beat the cream cheese in a medium bowl until smooth.

Add the sugar, vanilla, and salt and beat on medium until well combined. Dollop over the cake layer and use a butter knife to swirl the two together a bit.

Bake for 32 to 42 minutes until a cake tester inserted into the center of the bars comes out clean.

Cool completely on a wire rack before slicing and serving.

Uneaten bars can be stored, covered, in the fridge for up to 3 days or in the freezer, tightly wrapped, for up to 2 months.