Preheat the oven to 350 degrees.
Line two 9 inch springform cake pans with a parchment circle on the bottom. Spray the sides with baking spray. Set aside.
In a medium bowl combine the flour, baking powder, and salt.
In large bowl cream together the butter and brown sugar.
Add in the eggs and vanilla and mix for 2-3 minutes until fluffy.
Add half the flour mixture to the butter mixture and mix until well combined. Add the milk and mix until well incorporated. Add the remaining flour and mix until smooth.
Pour half the batter into each of the prepared cake pans. Bake for 30 minutes.
Remove the cakes from the oven and cool for 10 minutes. Release the spring and remove the cakes to a wire rack. Cool completely.
Meanwhile, combine the peaches, cornstarch, brown sugar, lemon juice, and cinnamon in a medium saucepan over medium heat. Stir frequently until the mixture begins to boil.
Mash the peaches in the pan. Continue cooking until the mixture has thickened. Remove from heat and cool.
If you didn't peal the peaches put the mixture into a food processor and process until the jam is smooth.
To make the buttercream frosting put the butter in a bowl and beat on medium speed with a mixer.
Add in 2 cups of powdered sugar and mix on medium speed until smooth.
Add in the peach filling and the vanilla and beat on medium speed.
Add in the remaining powdered sugar and beat until smooth.
To make the cake place one layer on a cake board. Spread a half cup of frosting over top of the layer. Pipe a border of frosting around the outside edge.
Put 1/2-3/4 cup of peach filling on top of the frosting and spread to the frosting border.
Top with the second layer of cake.
Spread the frosting on the top and sides of the cake to cover. Refrigerate for 20 minutes to firm up the frosting.
To decorate the cake crust the graham crackers and press onto the bottom edge of the cake.
Pipe the remaining frosting in swirls around the top border of the cake.
Slide a peach and spread it out on top in a pinwheel or star pattern. Place a sprig of mint in the center of the peaches.
Sprinkle the top of the cake with gold and clear sprinkles if desired.