Preheat the oven to 350°F. Line a 9 × 13-inch rimmed baking sheet with a Silpat or parchment paper and spray with nonstick cooking spray. Sift the sugar, flour, chestnut flour, baking soda, and salt into the bowl of an electric mixer fitted with a paddle attachment. On medium speed, add the egg and stream in the melted butter until well combined. Add the chestnut puree, and then the candied chestnuts, and mix to incorporate well. Spread the batter in an even layer on the prepared baking sheet. Bake for 10 minutes, or until golden brown. Cool at room temperature, then chill in the refrigerator and, with a ring cutter, cut at least 6 circles slightly smaller than the circumference of 6 individual dome molds.