Preheat oven to 350°F. Lightly grease two 9" cake pans with oil and cover the bottom of the pans with parchment paper (optional). Add a handful of flour to the pans and rotate the pans to coat with flour to prevent sticking. Shake out excess flour.
Dry Ingredients: In a small mixing bowl, whisk together 2.5 cups flour, 4 teaspoons cinnamon, 1/4 teaspoon nutmeg, 1 teaspoon ginger, 1 teaspoon salt, 1 teaspoon baking soda, 1 teaspoon baking powder and set aside.
Wet Ingredients: In a medium sized batter bowl, use an electric mixer to beat the 4 eggs, 1 teaspoon vanilla extract, 1 cup light brown sugar, 1/2 cup granulated sugar and 1 cup vegetable oil on high speed for 2 minutes.
Combine: Pour the dry ingredients into the wet ingredients and stir them together using a spatula until combined. Stir in the 3 cups of carrots, 1/2 cup of raisins and 1/2 cup of chopped pecans.
Bake: Pour the batter evenly into the cake pans and bake for 30-35 minutes or until a toothpick inserted into the middle comes out clean.
Cool: Remove from oven, let cool for 20 minutes before transferring the cakes to a cooling rack to cool completely before frosting.