Apple Pecan Carrot Cake

Preheat oven to 350°. Sprinkle 1 1/3 cups toasted pecans into 2 well-buttered shiny 9-inch round cake pans; shake to coat bottom and sides of pans.
Stir together flour and next 3 ingredients.
Stir together eggs and next 4 ingredients in a large bowl until blended. Add flour mixture, stirring just until blended. Fold in apples, carrots, and remaining 1 cup pecans. Pour batter into prepared pans.
Bake at 350° for 30 to 35 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on wire racks 10 minutes. Remove from pans to wire racks, and cool completely (about 1 hour).
Place 1 cake layer, pecan side down, on a serving plate. Spread top of cake layer with 2/3 cup Apple Cider Caramel Sauce; top with remaining cake layer, pecan side down. Spread Mascarpone Frosting over top of cake. Drizzle 2 Tbsp. Apple Cider Caramel Sauce over frosting, and swirl sauce into frosting. Serve immediately.
Apple Cider Caramel Sauce
Cook cider in a 3-qt. saucepan over medium heat, stirring often, 10 minutes or until reduced to 1/4 cup. Stir in remaining ingredients. Bring to a boil over medium-high heat, stirring constantly; boil, stirring constantly, 2 minutes. Remove from heat, and cool completely. Refrigerate up to 1 week. To reheat, microwave at HIGH 10 to 15 seconds or just until warm; stir until smooth.
Mascarpone Frosting
Whisk together first 3 ingredients in a large bowl just until blended. Beat whipping cream at medium speed with an electric mixer until stiff peaks form. Gently fold into mascarpone mixture.