POSITION racks in top and bottom thirds of oven. Preheat to 350F. Line 2 large baking sheets with parchment.
WHIRL packages of chestnuts in a food processor until very finely ground (it should look like sand). It should measure 1 1/2 cups. Add rice flour, cornstarch, icing sugar, baking powder and salt. Pulse until combined. Add butter and vanilla. Pulse until dough comes together.
SCOOP 1 tbsp dough and roll into a ball. Place on prepared sheet. Repeat with remaining dough, arranging cookies 1 in. apart. Use the back of a round 1/2 tsp measuring spoon or small melon baller to make a deep indent in centre of each ball.
BAKE in top and bottom thirds of oven until bottoms of cookies are golden, switching and rotating sheets halfway through, 17 to 20 min. If indent puffs up during baking, gently press with the back of the measuring spoon as soon as you remove cookies from oven. Leave on sheet for 5 min, then transfer cookies to a rack to cool completely. Repeat with remaining dough. Just before serving, fill each indent with 1/2 tsp chestnut paste, then top with a piece of chestnut. Store cookies in an airtight container up to 1 week or freeze at least 1 month.
Nutrition (per cookie)
Prep tip: To minimize cracking, indent each cookie as soon it’s rolled into a ball.