Preheat oven to 350°F (175°C).
In a large mixing bowl, combine the persimmon pulp, brown sugar, eggs, milk, melted butter, and vanilla extract. Mix until smooth.
In a separate bowl, whisk together the flour, baking powder, baking soda, cinnamon, and salt.
Gradually add the dry mixture to the wet ingredients, stirring until just combined. Do not overmix. If using additions, gently fold them in at this stage.
Grease a 9-inch baking dish or pie dish with butter or non-stick spray. Pour the batter into the prepared dish and spread it evenly. (If using black walnuts, don't add them on top)
Bake for 35–40 minutes, or until a crust forms on the top. The center should remain slightly wobbly but not runny.
Remove from the oven and let it cool before serving. Serve warm, at room temperature, or chilled. Reheat leftovers in the microwave, if desired.