• Preheat your oven to 350°F (175°C).
• To begin preparing the cake, generously grease a 9x13-inch baking pan with nonstick cooking spray or butter. Line the bottom of the pan with parchment paper and lightly grease the parchment as well to ensure the cake releases easily after baking.

Prepare the batter:

• Grate the carrots using a box grater directly into a large mixing bowl. Add the light brown sugar, vegetable oil, eggs, pumpkin pie spice, and kosher salt to the bowl. Whisk the mixture together until everything is thoroughly combined and smooth.
• Add the all-purpose flour, baking powder, and baking soda to the wet ingredients. Using a whisk or spatula, gently stir the batter until the flour is fully incorporated and there are no visible streaks — be careful not to overmix.

Bake the cake:

• Pour the carrot cake batter into the prepared pan, spreading it evenly. Bake in the preheated oven for 35 to 45 minutes, or until a toothpick inserted in the center comes out clean.
• Allow the cake to cool completely in the pan on a wire rack, which should take about 1 hour. This will help the cake set and make it easier to frost.

Prepare the frosting:

• While the cake is cooling, make the cream cheese frosting. In a large bowl, use a hand mixer to beat the softened cream cheese and unsalted butter together on medium-high speed until smooth and fully combined, about 2 minutes. Add the powdered sugar, kosher salt, and vanilla extract. Beat on low speed for 30 seconds to incorporate, then increase to medium-high and continue beating for about 3 minutes until the frosting is fluffy and creamy.

Frost the cake:

• Once the cake is completely cool, use an offset spatula or the back of a spoon to spread the cream cheese frosting evenly over the top. Slice into squares and serve.
• Store any leftovers in the refrigerator, covered, for up to 5 days.