Grease the spring form pan and put a circle of parchment paper at the bottom
Mix together the first 4 ingredients: melted butter, brown sugar and salt and pour it over the parchment paper - spread out to evenly cover the circle of parchment paper
Cut the persimmons into thick slices (about 1/4 inch thick) and arrange the slices over the butter, brown sugar and salt.
Preheat over to 350 F
Sift together the flour, baking powder, baking soda, and salt in a medium mixing bowl.
Beat the eggs, butter until blended, add the sugar and buttermilk, beat till well mixed
Pour the wet mixture over the flour mixture and stir until well combined. Do not overmix. Don't worry if there are a few small lumps.
Carefully pour the mixture over the persimmons, smooth out the top with a spatula
Bake in the preheated oven for 25 to 30 minutes until golden brown. Insert a knife in the center, it should come out clean. If not bake for extra few minutes.
After cooling for 5 to 10 minutes, loosen the edge with a knife, put a plate over the top and invert the pan over the plate, release the sides of the spring form pan.
Serve warm or at room temperature.