Preheat the oven to 350 degrees.

Generously butter 3-9" inch round cake pans. Sprinkle 2 cups of the chopped pecans evenly into the cake pans and shake to coat.

In a medium mixing bowl, beat 1/2 cup butter and the shortening with an electric mixer, at medium speed, until well mixed and fluffy; gradually add sugar and beat well. Add the egg yolks, 1 at a time, mixing well after each addition. Mix in vanilla.

Mix the flour and baking soda to the butter mixture on low speed, alternating with the buttermilk, beginning and ending with the flour. Add the remaining 1 cup of the pecans.

In another medium mixing bowl, beat the egg whites until the peaks are stiff. Gently fold half the egg whites into the cake batter. Fold the remaining egg whites into batter, being careful not to overmix. Add the batter to prepared baking pans.

Bake the cakes in the preheated oven for approximately 23-25 minutes, or until a toothpick inserted into the center of the cakes comes out clean. Place the pans on a wire rack to cool for 10 minutes. Invert the cakes onto a wax paper lined wire rack. Brush the tops and the sides of the cakes with corn syrup and cool completely. (I wrap the completely cooled cakes in plastic wrap and refrigerate overnight).

Meanwhile, make the pecan pie filling; in a heavy bottom 3 quart saucepan, whisk together the first 6 ingredients until smooth.

Over medium heat, bring the mixture to a boil, whisking constantly; boil for 1 minute or until mixture is nice and thick. Remove from heat and stir in the butter and vanilla. Place a sheet of wax paper directly on the surface to avoid a film from forming. Chill at least 6 hours. (I chill it overnight)

Assemble the cake by placing the first layer of cake, pecan side up and spreading half the pecan pie filling on it. Repeat with the second layer of cake, and filling, then top with the last layer of cake, pecan side up.

 When cake is assembled, make the glaze. In a heavy bottomed 2 quart saucepan, bring the brown sugar, butter, and milk to a boil over medium heat. Boil 1 minute, whisking constantly. Remove from heat.

. Add vanilla and powdered sugar and using a hand-held electric mixer, beat on medium speed until smooth. Pour quickly over assembled cake and sprinkle with pecans.