Wash chestnuts and soak in warm water for 10 minutes. Score the round side with an X using a scoring tool or a cut along the top with a sharp chestnut knife.
Boil water in a pan, and heat an empty cast-iron skillet. Add scored chestnuts to boiling water and boil for 5 minutes, then remove and add to the hot skillet. Cover and steam for an additional 5 minutes. Add a little hot water to the pan to create steam, if necessary.
Peel the shell and inner skin while chestnuts are still warm, being careful to keep the nuts intact. Set aside broken pieces.
Prepare Syrup
Add granulated sugar, brown sugar, cardamom pods, split vanilla bean, and 3 cups water to a wide pan to avoid crowding the chestnuts. Bring syrup to a simmer and whisk until sugar dissolves, about 5 minutes.
Candy Chestnuts
Carefully add chestnuts to the syrup to avoid breaking them. Simmer on low for 5 minutes. Turn off the heat and cool completely, then cover the saucepan, and allow chestnuts to soak overnight in syrup.
Day 2-7 (Simmer Daily )
Simmer chestnuts gently for 3 minutes every 24 hours. By the 6th day, the syrup will thicken, and the chestnuts will be glossy. During the final simmer, stir in brandy, if desired.
Dry Chestnuts
Carefully remove chestnuts with a slotted spoon and arrange on a small tray with a wire rack, so excess syrup can drain. Dy in a 250°F oven for 45 minutes.
Video
Notes
Make sure you use fresh chestnuts; otherwise, they will not become tender.
If possible, use large chestnuts; they hold their shape better.
If a few break, save them for topping desserts or folding into ice cream.
Don't rush the candying stage; slower is better!
You can create a simple glaze with some of the chestnut syrup mixed with powdered sugar to glaze the candied chestnuts after they're dried.
To store, refrigerate in an airtight container for up to two weeks.
Freeze for up to 3 months.
Store marron glacéin a parchment-lined box for gifting!