Instructions

1. Make the persimmon pudding: Position a rack in the center of the oven and preheat to 350°F. Lightly grease an 8-inch round cake pan with spray. (Alternatively, line the bottom of the pan with a circle of parchment.)
2. In a large bowl, sift together the flour, sugar, instant pudding mix, cinnamon, baking soda, and salt. Set aside.
3. Spoon the flesh from the persimmons into a blender or food processor, discarding the skins, and blend until smooth. Transfer 1½ cups (354 g) of the persimmon purée to a medium bowl (reserve any remaining purée for another use), add the milk, vanilla, and egg, and whisk together until smooth and well incorporated. Add the persimmon mixture to the flour mixture in thirds, gently folding after each addition just until no dry spots remain. (Be careful not to overmix.)
4. Slowly drizzle in the brown butter, whisking continuously, until well incorporated. Transfer the batter to the prepared pan. 
5. Bake until the cake is golden brown and a tester inserted into the center comes out clean or with a few moist crumbs, 30–50 minutes. Transfer the pan to a wire rack to cool for 15 minutes, then invert the pan onto a serving plate or cake stand.
6. Meanwhile, make the toffee sauce: To a medium heavy pot over medium-low heat, add just enough sugar to lightly coat the bottom of the pot. Cook, stirring continuously with a silicone spatula or wooden spoon, until the sugar begins to melt, about 2 minutes. Sprinkle in a little more sugar and continue cooking, stirring continuously and gradually adding the sugar a little at a time and allowing each addition to melt before adding more, until a caramel develops, 5–7 minutes. Continue cooking until the caramel is a deep amber color (watch closely so it doesn’t burn), about 2 minutes, then carefully add the cream. (The caramel will bubble vigorously, so pour slowly and be cautious.) Stir gently until the cream is fully incorporated and the caramel is smooth, about 2 minutes more. 
7. Pour in the evaporated and sweetened condensed milks, stirring well to combine. Bring to a gentle boil over medium heat, stirring occasionally to keep the mixture smooth, then remove the pot from the heat. Stir in the lemon zest, salt, and vanilla until well incorporated. Set the mixture aside to cool slightly, then strain it through a fine-mesh strainer into a medium bowl and set aside. (The toffee sauce can be stored in an airtight container in the fridge for up to 1 week.)
8. Make the whipped crème fraîche: To a medium bowl, add the crème fraîche and confectioners sugar. Using a hand mixer, whip on medium until soft peaks form, 2–3 minutes. Be careful not to over-whip, as crème fraîche can quickly become too thick and lose its light texture. Use immediately or store in an airtight container in the fridge for up to 1 day.
9. Drizzle the cake with the toffee sauce, letting it pool and flow over the edges. Cut into slices and serve with generous spoonfuls of whipped crème fraîche.