In drum of food processor, pulse graham crackers and almonds until coarsely ground. Add brown sugar and butter; pulse to combine.
Preheat oven to 350 F.
Spray 2 9-inch cake pan with baking spray. Divide and spread crunch mixture evenly on the bottom of the pans. Press down gently with fingers to cover the bottom of pan evenly and set aside.
In medium bowl, sift together the flour, baking powder, and salt; set aside. In a large bowl with electric mixer on medium speed, beat together sugar, buttermilk, orange juice, oil, vanilla, and zest. Add the eggs one at a time and mix to combine. Add in the dry ingredients a little at a time and mix until almost combined. Stop mixer to scrape the sides of pan with a spatula and fully combine the ingredients.
Divide the batter evenly among the two prepared pans. Bake in preheated oven for 25-30 minutes, until a knife inserted in middle of cake comes out clean. Let cakes cool in pans for 10 minutes. Run a knife along the sides of the first pan to help loosen the cake before inverting it onto your serving plate. Run a knife along the sides of the other cake and invert that cake onto a cooking rack. Completely cool cakes (I resisted just 30 minutes).
When cake cools, make the frosting With your electric mixer, beat the cream cheese and butter together until smooth. Add the orange zest, orange juice, and vanilla extract. On low speed, add powdered sugar (1/2 cup at a time) and beat until you have a nice and smooth frosting.
make your cake: With a spoon, drop half the frosting onto the cake on the serving plate (you should be doing this on the crunch side of the cake).
With a spatula, spread this thick layer of frosting. Place the second cooled cake crunch side down on top of frosting. Spread the remaining frosting on the top of the cake. Decorate with clementine slices. Slice with a serrated knife and dig in!