Preheat oven to 300°F. Lightly grease a 13- x 9-inch baking dish with cooking spray; set aside. Whisk together first 9 ingredients in a large bowl. Whisk together eggs, milk, half-and-half, zest, and liqueur (if using) in a separate large bowl until well combined. Add flour mixture to milk mixture alternately with persimmon puree, beginning and ending with flour mixture. Stir in chopped toasted pecans until just combined. Gradually add melted butter, and stir until just combined. Pour mixture into prepared baking dish.

Bake in preheated oven until mixture is browned and a wooden pick inserted in center comes out clean, 1 hour to 1 hour and 10 minutes. Serve warm, or transfer to a wire rack to cool completely, about 1 hour. Serve with Cinnamon Whipped Cream. Sprinkle with cinnamon, and top with persimmon slices.