Preheat your oven to 325 degrees. Spray three 8-inch or four 6-inch round cake pans with non-stick cooking spray and then line with parchment paper. Spray again. Set aside.

In a medium-sized bowl combine the graham cracker crumbs, melted butter, and sugar. With a rubber spatula, stir until all the graham cracker crumbs are combined with the melted butter. You should be able to squeeze the mixture and have it stick together.

Divide the mixture evenly between the three pans and press down firmly with your hand or the back of a spoon (about ¾ cup in each pan).

Bake for 10 minutes. Let cool while you make the cake layers.

Keep your oven at 325.

If you need to pulverize your graham crackers, do it now. They should resemble sand.

In a medium-sized bowl, whisk the graham cracker crumbs, flour, baking powder, cinnamon, baking soda, and salt. Whisk until the ingredients are well-blended. Set aside.

With the mixer on the lowest speed, add ⅓ of the dry ingredients and mix just until combined. Slowly add half of the buttermilk, followed by another ⅓ of the dry ingredients, the second half of the buttermilk and the final ⅓ of dry ingredients. Mix until combined, about 30 seconds. Scrape down the sides of the bowl and slowly mix for another 20-30 seconds.

Divide the batter evenly among your pans (about 20 ounces in each for 8 inch pans) right on top of the baked graham cracker crust and bake for about 30 to 35 minutes, or until a toothpick inserted in the center comes out with only a few moist crumbs on it. Cool 15 minutes on a wire rack before transferring the cake layers out of the cake pan and onto cooling racks to cool completely.

Place the berries, granulated sugar, lemon juice, lemon zest, and ¼ cup of water in a saucepan and heat over medium high heat.

With a rubber spatula, stir the mixture until it begins to boil.

Lower the heat to medium-low and allow the filling to simmer for 10-15 minutes.

In a separate small bowl, make a slurry by combining the remaining ¼ cup of water with the corn starch. Stir until the cornstarch has fully dissolved into the water.

Add this corn starch mixture into the berry mixture.

Turn the heat to medium high. Be sure to stir constantly during this stage to prevent the filling from burning.

Cook until the mixture begins to boil then reduce the heat to medium low.

Continue to stir and cook for a few additional minutes to cook out the corn starch flavor.

Turn off heat and pour the berry filling into a separate bowl to cool down. Cover with plastic wrap and place in the fridge for at least 1 hour, or preferably overnight.

In the bowl of an electric mixer, add the butter and ream on medium speed for about two minutes. Scrape down the sides and bottom of the bowl. Beat again for 2 more minutes.

Place the first cake layer on a cake board, with the graham cracker layer on the bottom. Gently and evenly spread half of the cake batter buttercream onto the cake layer, followed by a some raspberry compote.

Repeat with the second layer of cake.

Place your final cake layer, with the graham cracker layer on the bottom, on top of the second layer of filling.

Apply a thin layer of the cake batter buttercream around the entire cake and freeze the cake for 10 to 15 minutes.

Once the crumb coat is set, finish frosting and decorating the cake with the remaining cake batter buttercream. Throw a few rainbow sprinkles on it and serve at room temperature.