Prepare Your Baking Pans: Start by preheating your oven to 350°F (175°C). Lightly grease two 9-inch round cake pans with butter or non-stick spray. For easy removal later, line the bottoms with parchment paper circles.
Combine the Dry Ingredients: In a large bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg until well blended. This ensures the spices and leavening agents are evenly distributed throughout the cake.
Mix the Wet Ingredients: In a separate bowl, beat together the vegetable oil, light brown sugar, granulated sugar, eggs, and vanilla extract until the mixture is smooth and well combined. This creates the moist, sweet base of your cake.
Combine Wet and Dry Mixtures: Slowly add the wet mixture into the dry ingredients. Stir gently using a spatula or wooden spoon until just combined — it’s okay if some streaks of flour remain, as overmixing can make the cake dense.
Fold in Carrots and Pecans: Carefully fold in the grated carrots and chopped pecans, distributing them evenly throughout the batter. These add moisture, texture, and natural sweetness to the cake.
Bake the Cake Layers: Divide the batter evenly between the prepared pans. Place them in the oven and bake for 30 to 35 minutes, or until a toothpick inserted in the center comes out clean. Remove from oven and allow the cakes to cool completely in the pans on a wire rack.
Make the Cream Cheese Frosting: In a clean bowl, use a hand or stand mixer to beat the softened butter on medium speed until smooth and creamy (about 1 minute). Add the softened cream cheese and continue beating until light and fluffy (about 30 seconds). Gradually add the powdered sugar, starting with 4 cups, mixing on low speed. Add more sugar if a firmer consistency is desired. Mix in the vanilla extract and beat on medium-low speed until the frosting is smooth and spreadable.
Assemble and Chill the Cake: Once the cake layers have completely cooled, carefully remove them from the pans and peel off the parchment paper. Place one layer on a serving plate and spread about ¾ cup of frosting evenly over the top. Gently place the second layer on top, and cover the entire cake with the remaining frosting, smoothing the sides and top. For an extra touch, press chopped toasted pecans around the sides or pipe decorations with leftover frosting. Refrigerate the cake for at least 30 minutes before slicing to allow the frosting to set for clean cuts.