How to Make It
Preheat the oven to 325°. Grease a 9-by-13-inch metal baking pan with baking spray. Line the bottom with parchment paper and grease it with baking spray. In a small saucepan, cook the butter over moderate heat until golden and nutty smelling, about 5 minutes. Pour the brown butter into a heatproof bowl, leaving behind the solids; let cool to room temperature (you should have 1/2 cup).
In a food processor, pulse the brown sugar with the brown butter until well blended, then blend in the egg and vanilla. Add the flour and pulse just until incorporated, then mix in the chopped chocolate. Press the dough evenly into the bottom of the prepared pan.
In the bowl of a stand mixer fitted with the paddle, beat the cream cheese at medium speed until creamy and smooth, about 2 minutes. Beat in the pumpkin puree until smooth. At medium-low speed, add the eggs one at a time, beating well between additions. Beat in the vanilla. Slowly beat in the melted butter. Add the confectioner's sugar, cinnamon, allspice and salt and beat just until incorporated.
Scrape the pumpkin batter into the crust and bake for about 40 minutes, until just set. Transfer to a rack and let cool completely. Cut into bars and serve.
Valrhona's Dulcey chocolate, a caramelized blond version of white chocolate, is luxuriously creamy and buttery.