Pecan Pie Cake

Pecan Pie Filling
1/2 cup packed brown sugar
3/4 cup dark corn syrup
1/3 cup cornstarch
4 egg yolks
1 1/2 cups half-and-half
pinch salt
3 Tbsp butter
1 tsp vanilla
Pecan Pie Cake
3 cups pecans, finely chopped
1/2 cup butter, softened
1/2 cup shortening
2 cups sugar
5 eggs, separated
1 Tbsp vanilla
2 cups flour
1 tsp baking soda
1 cup buttermilk
3/4 cup dark corn syrup
Cinnamon Whipped Cream Custard Frosting
2 cups whipping cream (heavy cream)
1 Tbsp sugar
1/2 tsp cinnamon
1 cup of the Pecan Pie Filling
Directions : 
For Pecan Pie Filling: Whisk together the first 6 ingredients in a large, heavy saucepan until smooth. Bring to a boil over medium heat, whisking constantly, and boil for 1 minute, or until thickened. Remove from heat; whisk in butter and vanilla.
Place a sheet of wax paper (or plastic wrap) directly on surface of mixture to prevent a film from forming, and chill at least 4 hours. (When chilled – take out one cup of the filling to be used for the frosting)
For Pecan Pie Cake:  Preheat oven to 350. Sprinkle 2 cups pecans evenly into 3 generously buttered 9-inch round cake pans; shake to coat bottoms and sides of pans.
Beat butter and shortening at medium speed with an electric mixer until fluffy, and gradually add sugar, beating well. Add egg yolks, 1 at a time, beating just until blended after each addition. Stir in vanilla.
Combine flour and baking soda. Add to butter mixture alternating with the buttermilk, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Stir in remaining 1 cup pecans.
Beat egg whites at medium speed until stiff peaks form, and fold one third egg whites into batter. Fold in remaining egg whites. (Do NOT over mix).
Pour batter into prepared pans.
Bake at 350 for about 20-25 minutes.  Toothpick inserted near center should come out clean.
Cool in pans on wire racks for about 10 minutes, then invert onto the wire racks. Put some wax paper down under the wire racks.
Brush the tops and sides of layers with corn syrup, and cool completely. 
Cinnamon Whipped Cream Custard Frosting: Whip cream until soft peaks form. Gradually add sugar and cinnamon and beat until VERY stiff peaks form. (Just be careful you do not beat too much and turn your cream to butter) Gently stir in the 1 cup of Pecan Pie Filling until just combined.
To Assemble Cake: Place one cake, pecan side up, on serving tray.  
Spread half of pecan pie filling on one layer.
Place second cake, pecan side up, on top of filling.
Spread remaining pecan pie filling on top of second layer.
Top with 3rd cake, pecan side up.
Close up!!!
Frost with cinnamon whipped cream custard frosting.
Decorate as desired.
Make sure to cut yourself a big piece to enjoy!