Pre-heat an oven to 350° F.
Whisk the frosting ingredients with an electric mixer until thick and creamy, scraping the sides often. Set in the refrigerator to chill.
Grease and flour two 9-inch spring form pans. Set aside.
Combine the flour, cinnamon, salt, and baking soda in a bowl and whisk to blend. Set aside.
Whisk together the sour cream, sugars, and vanilla extract until combined, then add the eggs one at a time. When well blended, add the dry ingredients a bit at a time, scraping the sides often. Continue mixing until a smooth batter forms. Then fold in the shredded carrots with a spatula until everything is well distributed.
Pour the batter equally into the two prepared pans and bake for 25 minutes or until a toothpick inserted in the middle comes out clean.
Allow the cakes to cool in the pan for about 10 minutes, then remove from the pans and allow the cakes to completely cool directly on the racks.
Spread one cake with the apricot preserves, top with the second cake, then cover both with frosting.
Decorate the cake with chopped pecans, if desired.