Fill a small sauce pan with water and bring to a boil.
With a small pairing knife, make a diagonal slice through the skin on either side of each chestnut.
Boil the chestnuts covered for about 10 minutes.
Preheat the oven to 400°F.
Drain chestnuts and lay on a cookie sheet and mix in in 3 tablespoons of the olive oil or butter.
Roast in the oven for about 20 minutes the check for done-ness after 15.
The chestnuts should expand and the skin slightly opens.
The chestnuts are ready when you can squeeze the skin and they pop out easily and smoothly and have turned slightly golden yellow color and inside is not too dry, not raw and not too chalky.
Add the final tablespoon of oil or butter in a little bit of salt to taste stir, let cool for 3-5 mins.
Squeeze them on either side of the Chestnut to pop right out- ready to eat, perfectly cooked!