Preheat the oven to 350?F (175?C) and grease a 9-inch round baking pan.

In a large mixing bowl, whisk together the dry ingredients: flour, baking powder, baking soda, cinnamon, salt, granulated sugar, and brown sugar.

Add the wet ingredients: vegetable oil, eggs, and vanilla extract. Mix until just combined.

Fold in the grated carrots, walnuts, and raisins if using.

Pour the batter into the prepared baking pan and smooth the top.

Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted in the center comes out clean.

Allow the cake to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.