Prepare the carrot cake layers. Preheat oven to 350F (180C). Grease and line with parchment paper two 9 inch (23 cm) round cake pans.
In a medium bowl sift together the flour, baking powder, baking soda, salt, cinnamon and nutmeg. Set aside.
In a large bowl add eggs with both sugar and mix for few minutes until creamy and lighter in color. Add oil and mix until well combined. Gradually mix in flour mixture. Using a spatula incorporate the grated carrot and toasted pecans.
Pour the batter evenly into the prepared pans.
Bake for about 30-35 minutes until a toothpick inserted into the center comes out clean.
Let pans cool on a cooling rack for 10 minutes.
Remove the cakes from the pan and let them cool completely.
Prepare the caramel sauce. Place the sugar and water in a medium heavy bottomed saucepan over medium-high heat, and cook without stirring until sugar dissolves and gets a caramel color.
Remove the pan from the heat and add the cream. It will bubble a little bit.
Cook for about 1 minute stirring constantly with a wooden spoon until smooth.
Remove from heat and add butter, vanilla extract and salt. Stir well until smooth. Pour into a small jar and set aside to cool until the cake is ready.
Prepare the frosting. In a bowl beat the cream cheese until smooth. Add powdered sugar and 1/3 cup (80g) of caramel sauce.
In another bowl whip the cream until stiff peaks form. Gradually fold into the cream cheese mixture until well combined.
Assemble the cake. Place one cake layer on your serving plate. Spread evenly with a bit less than half of frosting. Add the second layer of cake. Gradually spread the remaining frosting on top and sides of the cake. Refrigerate for at least 2 hours.
Before serving top the cake with remaining caramel sauce letting some to drip down the sides. If the caramel hardened too much heat it a bit over bain-marie to get to a pouring consistency. Decorate with chopped and whole pecans if desired.
The leftover frosted cake can be covered and refrigerated for up to a week. Serve at room temperature.