Preheat the oven to 175°C and position a rack in the center. Grease a 23 x 13 centimeter loaf pan with the butter, dust it lightly with the 10 grams of flour, and tap out any excess.

Peel the very ripe persimmons if needed, remove any seeds, and mash the flesh until mostly smooth. Measure 240 grams of persimmon pulp and set it aside.

In a large mixing bowl, whisk together the 250 grams of flour, 150 grams of granulated sugar, 100 grams of brown sugar, baking soda, cinnamon, nutmeg, and salt until evenly combined and free of lumps.

In a separate bowl, whisk the eggs, vegetable oil, milk, vanilla extract, and persimmon pulp until smooth and well blended.

Pour the wet mixture into the dry ingredients and stir with a spatula just until no dry streaks remain. Fold in 140 grams of the chocolate chips, reserving 30 grams for the top. Do not overmix or the bread may become dense.

Transfer the batter to the prepared loaf pan and smooth the top. Sprinkle the remaining 30 grams of chocolate chips evenly over the surface.

Bake for 55 to 60 minutes, or until the loaf is domed, deeply golden, and a skewer inserted into the center comes out with a few moist crumbs but no wet batter.

Cool the bread in the pan for 15 minutes, then run a knife around the edges and carefully transfer the loaf to a wire rack. Let it cool completely for about 10 minutes more before slicing for cleaner pieces, or serve slightly warm if you prefer softer chocolate pockets.