For the cookies:
1 ½ c. all-purpose flour, plus more for work surface
½ tsp. coarse salt
¾ c. unsalted butter, room temp
¾ c. sifted confectioners’ sugar
1 large egg
for the filling:
4 TB unsalted butter, room temp
2/3 c. sifted confectioners’ sugar
Pinch of coarse salt
2 TB chestnut cream (crème de marron)
for the glaze:
6 oz. semisweet chocolate, coarsely chop
1. Make cookies: sift together flour and salt in bowl. Put butter in mixer and mix on med-high until fluffy, about 2 minutes. Add confectioners’ sugar; mix until smooth. Mix in egg, reduce speed to low and add flour mixture; mix until just combined. Wrap dough in plastic and refrigerate until firm, about 2 hours.
2. Preheat oven to 350. Roll out dough to 1/8 inch thick and cut into 1 ½ inch rounds. Place 1 inch apart on parchment lined cookie sheet. Bake, rotating sheet halfway until golden about 12 minutes. Transfer to wire rack to cool completely.
3. Make filling: put butter in the bowl of an electric mixer, mix on medium speed until smooth, about 3 minutes. Add confectioners’ sugar and chestnut cream; mix until smooth.
4. Make glaze: melt chocolate in a saucepan over low heat, stirring constantly.
5. Assemble cookies: spread filling on one cookie and sandwich together. Dip sandwiches a third of the way into the warm glaze; transfer to a wire rack set over baking sheets. Refrigerate till set, about 15 minutes. Can be refrigerated in single layer, airtight, up to 2 days.