Preheat the oven to 350°F and heavily grease the pans you're using (if 9x13, add a piece of parchment paper in for convenience).
Add vegetable oil, sugar, vanilla and lemon extract into stand mixing bowl. Beat together. Note: the mixture will be really oily but mix until the sugar looks dissolved.
Add one egg at a time into the mixing bowl, beating well after each addition. Batter will start to form. Fold in shredded carrots.
Add the dry ingredients into the mixer: all-purpose flour, baking soda, salt, and cinnamon. After fold in chopped nuts.
Pour mixture into baking pan(s).
Bake for 40-45 minutes or until an inserted toothpick comes out clean. Allow the cakes to cool before removing from the pans.
For the frosting, combine all ingredients in a mixing bowl: butter, cream cheese, powdered sugar, and vanilla extract. Blend frosting ingredients on medium speed until smooth. All of the clumps of powdered sugar should be dissolved.
Layer the cakes with frosting in between each layer.
Tip: Refrigerate the cake for 30 minutes before frosting the top and outside layer. This will help with structure! Top with crushed nuts or other flavors and enjoy. Best chilled but can be served room temperature. Enjoy!