Preheat your oven to 325 degrees Fahrenheit. Grease a 9 inch springform pan and line the bottom with parchment paper. In a large bowl, beat the 16 ounces of softened cream cheese with half a cup of sugar until smooth. Add two eggs, sour cream, and alcohol-free vanilla, mixing just until combined. Pour the mixture into the pan and bake for 40 to 45 minutes until the edges are set but the center still slightly jiggles. Let it cool completely, then freeze for at least two hours to make assembly easier.
Increase the oven temperature to 350 degrees Fahrenheit. Grease and flour two 9 inch round cake pans. In a large mixing bowl, cream together one cup of softened butter and 1.5 cups of sugar until light and fluffy. Add four eggs one at a time, beating well after each addition. Stir in the alcohol-free vanilla. In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the butter mixture, alternating with the milk, starting and ending with the dry ingredients. Fold in one cup of the toasted pecans.
Divide the cake batter evenly between the two prepared cake pans. Smooth the tops with a spatula. Bake for 25 to 30 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool in the pans for 10 minutes before transferring them to wire racks to cool completely. It is very important that the cakes are entirely cool before you begin the assembly process.
In a medium bowl, beat the remaining 8 ounces of cream cheese and half a cup of butter until very smooth and creamy. Slowly add the powdered sugar one cup at a time, mixing on low speed until incorporated. Add a tablespoon of milk or cream to reach your desired spreading consistency. Whip on high speed for another minute to make the frosting light and airy.
Place one cake layer on your serving plate. Carefully remove the chilled cheesecake layer from its pan and place it directly on top of the first cake layer. Place the second cake layer on top of the cheesecake. Spread the cream cheese frosting over the top and sides of the entire cake. Press the remaining half cup of chopped pecans into the sides of the cake or sprinkle them in a decorative ring around the top edge.
