Preheat the oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.
In a mixing bowl, combine flour, baking powder, cinnamon, and salt.
In another bowl, whisk together oil, eggs, and sugar until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the grated carrots.
Pour the batter into the prepared baking pan and bake for 40 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool completely before frosting.
For the frosting, beat together cream cheese and butter until smooth. Gradually add powdered sugar and vanilla extract, beating until creamy.
Spread the frosting over the cooled cake. Slice and serve.