Preheat the oven to 350°F. Grease and flour three 6-inch cake pans. Line the bottom of each with a round of parchment.
In a bowl, whisk together the flour, baking soda, and spices.
Combine the buttermilk and the vanilla in a cup.
In the bowl of an electric mixer, fitted with the paddle attachment, cream the butter and the sugar for several minutes until it is light and fluffy.
Add the eggs, one at a time, beating well with each addition and scraping down the bowl as needed.
Add the flour mixture in thirds, alternating with the buttermilk, mixing on low.
Divide the batter between the 3 pans, and bake the cakes until a cake tester inserted in the center comes out clean. (if you are baking the batter in one tall cake pan, the cake may take as long as an hour or more to bake!)
Let the cake layers cool in the pan for 10 minutes, then unmold them onto a rack to cool completely.
Make the white chocolate cream cheese frosting
Melt the white chocolate over a double boiler until it is thick and just melted. Do not overheat the chocolate, it should never feel warm to the touch. Let the melted chocolate stand for a few minutes or until it has thickened up and to make sure it's not too warm to make frosting.
In the bowl of an electric mixer fitted with the paddle attachment, beat the cream cheese until it is smooth, then add the white chocolate in thirds, being sure to pour it right onto the cream cheese, and not on the beater or the sides of the bowl as it will harden and clump. Beat in the white chocolate and when it is all incorporated, add in the butter and beat it in, finishing with the lemon juice.
Assemble and decorate the cake
Trim/level the layers with a serrated knife so that they are flat and fairly even. Place the first layer on a plate, top with a generous ½ cup of frosting, smoothing it with an offset spatula. Top with the 2nd layer of cake, another generous ½ cup of frosting, and then the 3rd layer. Smear the last of the frosting onto the top and sides of the cake so the surface is smooth and completely covered.
Line up the Teddy Grahams around the base of the cake, pressing them into the frosting to “glue” them. Use the graham cracker crumbs to stencil on the number of the birthday celebrated.